alphabet_list = [0 for x in range(ord('a'),ord('z')+1)]

S = list(raw_input())

for x in S:
    alphabet_list[ord(x) - ord('a')] += 1

print_flag = False
for index in range(0,ord('z')-ord('a')+1):
    if alphabet_list[index] == 0:
        print(chr(index+ord('a')))
        print_flag = True
        break

if not(print_flag):
    print('None')


S = input()
alf = "abcdefghijklmnopqrstuvwxyz"
li = []

for x in alf:
    if (x in S) == False:
      li.append(x)
      break

if len(li) != 0:
    print(li[0])
else:
    print("None")


S = input()
L = [chr(i) for i in range(97,97+26)]

for c in L:
    if c in S:
        if c == 'z':
            print('None')
        continue
    else:
        print(c)
        break


import sys
line = raw_input()
res = dict()
for i in line:
    res[i] = 1
    if len(res) == 26:
        print 'None'
        sys.exit(0)
for i in 'abcdefghijklmnopqrstuvwxyz':
    if res.get(i, None) is None:
        print i
        sys.exit(0)


all_char = map(chr,range(97,123))
all_set = set(all_char)
input_set = set(input())
print(min(all_set-input_set or{"None"}))


S = input()
x = [chr(i) for i in range(ord("a"),ord("z")+1)]
for i in x:
  if i not in S:
    print(i)
    break
  if i == x[-1]:
    print("None")
    break


S = list(input())

T = list('abcdefghijklmnopqrstuvwxyz')

sub = [c for c in T if c not in S]
if len(sub) != 0:
    print(sub[0])
else:
    print('None')


s=raw_input()
a=[0 for i in range(26)]
p=-1
for i in range(len(s)):
    a[ord(s[i])-97]=1
for i in range(26):
    if a[i]==0:
        print chr(i+97)
        exit()
print "None"


import string
import sys
from collections import Counter

# sys.stdin = open('b1.in')

def read_int_list():
    return list(map(int, input().split()))

def read_str_list():
    return input().split()

def read_int():
    return int(input())

def read_str():
    return input()

def main():
    a = list(string.ascii_lowercase)
    res = None
    s = read_str_list()
    l = list(s)
    l.sort()
    s = ''.join(l)

    c = Counter(s)
    for i in a:
        if c[i] == 0:
            res = i
            break

    print(res)

main()


S = input()
l = 'abcdefghijklmnopqrstuvwxyz'

for x in l:
    if not x in S:
        print(x)
        exit()

print('None')


n = input()
for i in range(26):
    c = chr(i+ord("a"))
    if not c in n: print(c); break
else: print("None")


S = input()
a = [chr(i) for i in range(97, 97+26)]
for s in S:
    if s in a:
        a.remove(s)
if len(a) == 0:
    print('None')
else:
    print(a[0])


S = str(input())
list_S = []

for i in range(len(S)):

    list_S.append(S[i:i+1])

alf = 'abcdefghijklmnopqrstuvwxyz'
list_alf = []
for i in range(len(alf)):
    list_alf.append(alf[i:i+1])

count = 0
conti = 0

for i in range(len(alf)):
    count = list_S.count(list_alf[i])
    if count == 0:
        print (list_alf[i])
        break
    conti += 1

if conti >= 26:
    print ('None')


#coding=UTF-8

S=input()
ans='None'
for chr_num in range(ord('a'),ord('z')+1,1):
    mozi=chr(chr_num)
    if not(mozi in S):
        ans=mozi
        break

print(ans)


import string
S = input()
for a in string.ascii_lowercase:
    if a not in S:
        print(a)
        exit(0)
print('None')


print((lambda x:"None" if not x else x[0])(sorted(set(chr(97+i) for i in range(26))-set(list(input())))))


# coding: utf-8
# Here your code !
s = set(input())
ab = {chr(i) for i in range(97,97+26)}
ab -= s
if len(ab) == 0:
    print("None")
else:
    print(min(ab))


s=set(input())
for c in range(ord('a'),ord('z')+1):
    c=chr(c)
    if c not in s:
        print(c)
        break
else:
    print(None)


import string

S = input()

X = set(string.ascii_lowercase) - set(S)
if X:
    print(sorted(list(X))[0])
else:
    print(None)


print((lambda s:next((chr(i)for i in range(97,123)if chr(i)not in s),"None"))(input()))


hoge = [0] * 26
a = ord('a')
string = input()
for i in range(len(string)):
    hoge[ord(string[i])-a] = 1

for i in range(26):
    if hoge[i] == 0:
        print(chr(i+a))
        break
    if i == 25:
        print('None')


s = input()
arr = "abcdefghijklmnopqrstuvwxyz"
ans = []
for word in arr:
    if word in s:
        pass
    else:
        ans.append(word)
if len(ans) == 0:
    print("None")
else:
    print(ans[0])


def main():
    S = input()
    alphabet = "abcdefghijklmnopqrstuvwxyz"
    #print(alphabet)
    #com = S + alphabet
    #print(sorted(set(com), key=com.index))
    dic = str.maketrans("", "", S)
    ans = alphabet.translate(dic)
    if(len(ans) > 0):
        print(ans[0])
    else:
        print("None")

if __name__=="__main__":
    main()


#from time import time
#t = time()
n = input()
d=[]
abc =[chr(x) for x in range(97, 123)]
for i in abc:
    if i not in  n:
        d.append(i)
if d != []:
    print(sorted(d)[0])
else:
    print('None')

#print(mn[0] * mm[1])
#tt= time()
#print(tt-t)


S = raw_input()
for c in [chr(ord("a") + i) for i in xrange(26)]:
    if c in S:
        continue
    else:
        print c
        break
else:
    print "None"


x=sorted(set(chr(97+i) for i in range(26))-set(input()))
print("None" if not x else x[0])


import string
S = input()
diff = set(string.ascii_lowercase) - set(S)
diff = sorted(list(diff))
if len(diff) == 0:
    print('None')
else:
    print(diff[0])


S = input()

for i in "abcdefghijklmnopqrstuvwxyz":
    if S.replace(i,"") == S:
        print(i)
        break
else:
    print("None")


def search(code):
    for i in range(len(code)):
        if code[i] == 0:
            return i
    else:
        return -1

s = raw_input()

code = [0 for i in range(26)]

for i in range(len(s)):
    key = ord(s[i]) - 97
    code[key] += 1

rt = search(code)

if rt >= 0:
    print chr(rt + 97)
else:
    print "None"


x = str(input())

for i in range(97,123):
    if(x.find(chr(i))==-1):
        print(chr(i))
        quit()

print('None')

quit()


s = input()
ab_list = [True]*26
for i in s:
  ab_list[ord(i)-97] = False
for i in range(len(ab_list)):
  if ab_list[i]:
    print(chr(i+97))
    exit()
print("None")


a_list=("abcdefghijklmnopqrstuvwxyz")
word=(raw_input())
flag=0
out="None"
for i in a_list:
    for n,k in enumerate(word):
        if i==k:
            break
        if n==len(word)-1:
            out=i
            flag=1
    if flag==1:
        break
print(out)


S = input()

a = 0
for i in range(97, 97 + 26):
    if chr(i) not in S:
        print(chr(i))
        a = 1
        break

if a == 0:
    print('None')


from collections import defaultdict
from itertools import product, groupby
from math import pi
from collections import deque
from bisect import bisect, bisect_left, bisect_right
from string import ascii_lowercase
INF = 10 ** 10

def main():
    S = input()
    for c in ascii_lowercase:
        if c not in S:
            print(c)
            return
    else:
        print("None")

if __name__ == '__main__':
    main()


s=list(input())
L=[]
for t in range(0,26):
    if chr(97+t) not in s:
        a=chr(97+t)
        L.append(a)

if not L:
    print("None")
else:
    print(L[0])


a = raw_input().strip()
al = 'abcdefghijklmnopqrstuvwxyz'
for x in al:
	try:
		i = a.index(x)
	except :
		print(x)
		exit()
print('None')


import math,string,itertools,fractions,heapq,collections,re,array,bisect,sys,random,time,copy,functools

sys.setrecursionlimit(10**7)
inf = 10**20
gosa = 1.0 / 10**10
mod = 10**9 + 7

def LI(): return [int(x) for x in sys.stdin.readline().split()]
def LI_(): return [int(x)-1 for x in sys.stdin.readline().split()]
def LF(): return [float(x) for x in sys.stdin.readline().split()]
def LS(): return sys.stdin.readline().split()
def I(): return int(sys.stdin.readline())
def F(): return float(sys.stdin.readline())
def S(): return input()

def main():
    c = collections.Counter(S())
    for k in string.ascii_lowercase:
        if c[k] == 0:
            return k
    return 'None'

print(main())


S=input()

sorted(S)

if 'a' not in S:
    print('a')
elif 'b' not in S:
    print('b')
elif 'c' not in S:
    print('c')
elif 'd' not in S:
    print('d')
elif 'e' not in S:
    print('e')
elif 'f' not in S:
    print('f')
elif 'g' not in S:
    print('g')
elif 'h' not in S:
    print('h')
elif 'i' not in S:
    print('i')
elif 'j' not in S:
    print('j')
elif 'k' not in S:
    print('k')
elif 'l' not in S:
    print('l')
elif 'm' not in S:
    print('m')
elif 'n' not in S:
    print('n')
elif 'o' not in S:
    print('o')
elif 'p' not in S:
    print('p')
elif 'q' not in S:
    print('q')
elif 'r' not in S:
    print('r')
elif 's' not in S:
    print('s')
elif 't' not in S:
    print('t')
elif 'u' not in S:
    print('u')
elif 'v' not in S:
    print('v')
elif 'w' not in S:
    print('w')
elif 'x' not in S:
    print('x')
elif 'y' not in S:
    print('y')
elif 'z' not in S:
    print('z')
else:
    print('None')


string = ['a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z']

s =[d for d in input()]
find = 0
i=0
found = False
while i<26 and not found:
    if string[i] in s :
        found= False
    else:
        find =string[i]
        found=True
    i +=1

if found:
    print(find)
else:
    print('None')


s=set(input())
eng = [chr(i) for i in range(97,123)]
for i in eng:
    if i not in s:
        print(i)
        break
else:
    print("None")


S = input()
alphabet = "abcdefghijklmnopqrstuvwxyz"
found = [i for i in alphabet if i not in S]
found.sort()
if len(found) == 0:
  print('None')
else:
  print(found[0])


S=list(str(input()))

a=list('abcdefghijklmnopqrstuvwxyz')

for i in a:
    if i not in S:
        print(i)
        exit()
else:
    print('None')


abc='abcdefghijklmnopqrstuvwxyz'
s=raw_input().strip()
isi=set()
for l in s:
    if l not in isi:
        isi.add(l)
for l in abc:
    if l not in isi:
        print l
        break
else:
    print 'None'


#!/usr/bin/env python3
# -*- coding: utf-8 -*-

import string

def main():
    S = set(input())
    T = set(string.ascii_lowercase)

    T -= S
    if not T:
        print("None")
    else:
        print(sorted(T)[0])

if __name__ == "__main__": main()


s = list(input().strip())
s.sort()
i = 0
for c in "abcdefghijklmnopqrstuvwxyz!":
    if i < len(s) and s[i] == c:
        while i < len(s) and s[i] == c:
            i += 1
    else:
        if c != "!":
            print(c)
        else:
            print("None")
        raise SystemExit


s=input()
s=list(s)
nums=[]
for i in s: nums.append(ord(i))

flag=True
for i in range(97,123):
    if i in nums: pass
    else: print(chr(i));flag=False; break
if flag: print("None")


s = list(set(input()))
abc = "abcdefghijklmnopqrstuvwxyz"
s.sort()
if len(s)==26: print("None")
else:
  for a in abc:
    if not(a in s):
      print(a)
      break


import sys

alphabet = "abcdefghijklmnopqrstuvwxyz"
word = raw_input()
found = 0

for letter in alphabet:
    if letter not in word:
        print letter
        found = 1
        break

if found == 0:
    print "None"


s = input()

alp = [chr(i) for i in range(97, 97+26)]

flag = [False for i in range(26)]

for c in s:
    flag[ord(c) - ord("a")] = True

def pr():
    for i in range(26):
        if not flag[i]:
            print(alp[i])
            return

    print('None')
    return

pr()


import string

standard_let = string.ascii_lowercase

s = input()
for i in standard_let:
    if i not in s:
        print(i)
        break
else:
    print('None')


# coding: utf-8
txt = input()
for c in 'abcdefghijklmnopqrstuvwxyz':
    if c not in txt:
        print(c)
        break
else:
    print('None')


d = raw_input()

d_list = []
for i in range(len(d)):
    d_list.append(ord(d[i]))

ans = ord('a')
while True:
    if ans not in d_list:
        break
    if ans > ord('a')+122:
        break
    ans += 1

if ans > 122:
    print 'None'
else:
    print chr(ans)


S = set(map(ord,input()))
alphabet = set(map(ord,'abcdefghijklmnopqrstuvwxyz'))

x = alphabet - S
try:
    print(chr(min(x)))
except:
    print('None')


s2 = "abcdefghijklmnopqrstuvwxyz"
s2 = set(s2)
s = set(raw_input())
if len(s) == 26:
    print "None"
a = list(s2 -s)
if len(a) >0:
  a.sort()
  print a[0]


print((lambda x:"None" if not x else x[0])(sorted(list(set(chr(i) for i in range(97,97+26))-set(input())))))


S = input()
d = {}

for i in range(ord("a"), ord("z") + 1):
    d[chr(i)] = False

for c in S:
    d[c] = True

ans = "None"
for i in range(ord("a"), ord("z") + 1):
    if not d[chr(i)]:
        ans = chr(i)
        break
print(ans)


S = input()
charset = list(set(S))
dic = [chr(i) for i in range(97, 97+26)]

[dic.remove(c) for c in charset]
if dic == []:
    print("None")
else:
    print(dic[0])


import string
s = list(input())
a = list(string.ascii_lowercase)
l = []
for index, i in enumerate(a):
    if i not in s:
        print(i)
        break
else:
    print(None)


S = str(input())
alphabet = "abcdefghijklmnopqrstuvwxyz"

flag = [0] * 26
for i in range(26):
    if alphabet[i] in S:
        flag[i] = 1

for i in range(26):
    if flag[i] == 0:
        print(alphabet[i])
        break

if flag == [1] * 26:
    print("None")


print([sorted(set(chr(97+i)for i in range(26))-set(input()))or["None"]][0][0])


S = input()

alpha = ["a", "b", "c", "d", "e", "f", "g",
        "h", "i", "j", "k", "l", "m", "n",
        "o", "p", "q", "r", "s", "t", "u",
        "v", "w", "x", "y", "z"]
S = list(set(S))
S.sort()
#print(len(S))
for i in range(len(S)):
    if S[i] != alpha[i]:
        print(alpha[i])
        break
    elif i == 25:
        print("None")
    elif i == len(S) - 1:
        print(alpha[i+1])


#! /bin/python
# coding:utf-8

import sys

def strchr(string, char):
	for token in string:
		if (token == char):
			return 1
	return 0

S = raw_input()

tmp = chr(ord('a'))
for i in range(0, 26):
	if (strchr(S, tmp) == 0):
		print tmp
		sys.exit()
	tmp = chr(ord(tmp) + 1)

print "None"


def B_NotFound(lst):
    comparison = 'abcdefghijklmnopqrstuvwxyz'
    lst = sorted(set(lst))  # 文字列をソート(重複はいらないので除く)

    string = [''] * len(comparison)
    for i in range(len(lst)):
        string[i] = lst[i]

    for i in range(len(string)):
        if string[i] != comparison[i]:
            return comparison[i]
    return 'None'

s = input()
print(B_NotFound(s))


print(min([set(chr(97+i)for i in range(26))-set(input())or["None"]][0]))


myinput=input()
for c in 'abcdefghijklmnopqrstuvwxyz':
    if c not in myinput:
        print(c)
        break
else:
    print('None')


import string

S = set(list(input()))
ans = set(list(string.ascii_lowercase)) - S
if len(ans) == 0:
    print("None")
    exit()
ans = sorted(list(ans))[0]
print(ans)


word_list = list(input().lower())
alphabet_uniq = list(set(word_list))
alphabet_uniq.sort()

alphabet_uniq.append('END')
if len(alphabet_uniq) != 27:
    for i in range(0, len(alphabet_uniq)):
        if chr(i + 97) != alphabet_uniq[i]:
            print(chr(i + 97))
            break
else:
    print(None)


s = input()

l = list(s)
#l=list(set(l))
#l.sort()
#print(l)

l_abc = list("abcdefghijklmnopqrstuvwxyz")

l = list(set(l_abc) - set(l))
l.sort()

#print(l)
#print(len(l))

if len(l) == 0:
	print("None")
else:
	print(l[0])


import collections
s = collections.Counter('abcdefghijklmnopqrstuvwxyz')
l = collections.Counter(input())
ret = 'None'
for el in sorted((s+l).items()):
  if el[1] == 1:
    ret = el[0]
    break
print(ret)


def solve(): # 071B - Not Found
    alphabet = []
    for i in range(26):
        alphabet.append(chr(97 + i))
    s = list(input())

    for j in s:
        if j in alphabet:
            alphabet.remove(j)
        else:
            pass

    if len(alphabet) == 0:
        print("None")
    else:
        print(alphabet[0])

solve()


x=set(chr(97+i) for i in range(26))-set(input())
print("None" if not x else min(x))


s = input().strip()

alphabets = 'abcdefghijklmnopqrstuvwxyz'

s_set = set(s)

for c in alphabets:
    if c not in s_set:
        print(c)
        exit()
print('None')


x=set([chr(i) for i in range(97,97+26)])-set(list(input()))
print("None" if not x else sorted(list(x))[0])


S=map(str,raw_input())
S.sort()
flag=1
SS=[]
for i in S:
    SS.append(ord(i))
for i in range(ord("a"),ord("z")+1):
    if not i in SS:
        ans=chr(i)
        print ans
        flag=0
        break
if flag==1:
    print "None"


S=input()
check=True

for i in range(0,26):
    if S.find(chr(i+97))==-1:
        print(chr(i+97))
        check=False
        break

print("None" if check else "")


import sys
s=str(input())
for i in range(97,97+26):
  if not chr(i) in s:
    print(chr(i))
    sys.exit()
print("None")


import string
import sys

S = input()
l = string.ascii_lowercase

for c in l:
  there = False
  for cs in S:
    if c == cs:
      there = True
  if there == False:
    print(c)
    sys.exit()

print("None")
sys.exit()


import string

s = input()
alp = string.ascii_lowercase

def search(s, c):
    for i in s:
        if i == c:
            return 1
    return 0

f = 0
for i in alp:
    if not search(s, i):
        print (i)
        f = 1
        break;
if not f:
    print ("None")


S = set(input())

X = set('abcdefghijklmnopqrstuvwxyz')

S=X-S

print("None" if S==set() else min(S))


import sys
inp = lambda t: t(sys.stdin.readline().strip())
inpm = lambda t: map(t, sys.stdin.readline().split())
inpl = lambda t: list(map(t, sys.stdin.readline().split()))

s = inp(str)

p = set()
for i in s:
	if i not in p:
		p.add(i)

for i in range(ord('a'), ord('z') + 1):
	if chr(i) not in p:
		print(chr(i))
		break
else:
	print('None')


S = input()

for i in range(ord('a'), ord('z') + 1):
    if chr(i) not in S:
        print(chr(i))
        break
else:
    print('None')


s = input()
s_list = list(s)
s_set = set(s_list)
abc_list = [chr(i) for i in range(97, 97+26)]
if len(s_set) == 26:
    print("None")
else:
    for a in abc_list:
        if a in s_set:
            pass
        else:
            print(a)
            break


import string

def main():
    cs = set(input())
    print(solve(cs))

def solve(cs):
    for c in string.ascii_lowercase:
        if c not in cs:
            return c
    return 'None'

if __name__ == '__main__':
    main()


# -*- encoding: utf-8 -*-
s = list(input().rstrip())
alpha = list(map(chr, range(ord('a'), ord('z') + 1)))

for a in alpha:
    if a not in s:
        print(a)
        break
else:
    print("None")


s = input()
count =[0 for i in range(26)]

for i in s:
    count[ord(i)-ord("a")]+=1

for i in range(len(count)):
    if count[i] == 0:
        print(chr(i+ord("a")))
        break
else:
    print("None")


s=input()
char=['a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z']
check=False
for c in char:
    if not c in s:
        print(c,end='')
        check=True
        break
if  check==False:
    print('None',end='')


# -*- coding: utf-8 -*-
"""
"""
#

def main():
    alphabets = 'abcdefghijklmnopqrstuvwxyz'
    text = input().strip()

    result = 'None'
    for c in alphabets:
        if c not in text:
            result = c
            break
    print(result)

if __name__ == '__main__':
    main()


S = input()
ans = None
for letter in "abcdefghijklmnopqrstuvwxyz":
    if letter not in S:
        ans = letter
        break
print(ans)


abc = 'abcdefghijklmnopqrstuvwxyz'
S = input()
for x in abc:
    if not x in S:
        print(x)
        break
else:
    print('None')


from collections import Counter
S = input()

counter = dict(Counter(S))
counter = sorted(counter)
alphabets = "abcdefghijklmnopqrstuvwxyz"

found = False
for letter in alphabets:
    if letter in counter:
        continue
    else:
        found = True
        print(letter)
        break

if found is not True:
    print("None")


import sys

S=[]

S = raw_input()

check=[chr(i) for i in range(97, 97+26)]
n=len(check)

for i in range (n):
    o=0
    if(S.count(check[i])<=0):
        print check[i]
        o=1
        break

if(o==0):
    print "None"


import math
def search(x,n):
	curPos=0
	log2=int(math.log(n,2))
	newPos=0
	if s[curPos]==x:
		return True
	while log2 >=0:
		newPos=curPos + (1 << log2)
		if newPos < n and s[newPos]<=x:
			curPos=newPos
		if s[curPos]==x:
			return True
		log2-=1
	return False

s=input()
s=list(s)
s.sort()
n=len(s)
s_str=[chr(x) for x in range(97,123)]
Found=False
for i in s_str:
	res=search(i,n)
	if not res:
		print(i)
		Found=True
		break
if not Found:
	print('None')


S = input()
for i in range(26):
    a = chr(ord('a') + i)
    if not a in S:
        print(a)
        break
else:
    print('None')


S = input()
res = "None"

for c in range(26):
    if chr(ord('a') + c) not in S:
        res = chr(ord('a') + c)
        break
print(res)


# coding=utf-8
S = list(raw_input())

alpha = 'abcdefghijklmnopqrstuvwxyz'
t = True
for a in alpha:
    if a not in S:
        print a
        t = False
        break
if t:
    print None


S = input()
alphabet = "abcdefghijklmnopqrstuvwxyz"

for alp in alphabet:
    if alp not in S:
        print(alp)
        break
else:
    print("None")


S = input()
l = 'abcdefghijklmnopqrstuvwxyz'

for x in l:
    if not x in S:
        print(x)
        break
    else:
        if x == 'z':
            print('None')


print(min(set(chr(97+i)for i in range(26))-set(input())or["None"]))


s = set(input())
alp = set('abcdefghijiklmnopqrstuvwxyz')
try:
	print(sorted(list(alp - s))[0])
except:
	print('None')


string=input()
l="abcdefghijklmnopqrstuvwxyz"
for i in l:
    if i not in string:
        print(i)
        break
else:
    print("None")


print((lambda s:next((c for c in map(chr,range(97,123))if c not in s),"None"))(input()))


s = input()
s = set(list(s))

ans = 'None'

for alpha in list('abcdefghijklmnopqrstuvwxyz'):
    if alpha not in s:
        ans = alpha
        break

print(ans)


def main():
    s = input()
    flag = True
    for i in range(ord('a'), ord('z')+1):
        if chr(i) not in s:
            print(chr(i))
            flag = None
            break
    if flag:
        print("None")

if __name__ == "__main__":
    main()


s = input()
data = list(set(s))
alp = list("abcdefghijklmnopqrstuvwxyz")
data.sort()
for i in alp:
    if len(data) == 0:
        print(i)
        break
    else:
        if i != data[0]:
            print(i)
            break
        else:
            if i == "z":
                print("None")
            del data[0]


S = input()
ls = [chr(i) for i in range(ord("a"),ord("z")+1)]
for c in S:
    if c in ls:
        ls.remove(c)
if ls==[]:
    print("None")
else:
    print(ls[0])


# -*- coding:utf-8 -*-

S = input()
CHR = [chr(i) for i in range(97, 97+26)]

judge = 1
i = 0

while(judge > 0 and i <= 25):
    judge = S.count(CHR[i])
    i = i+1

if(judge==0):
    print(CHR[i-1])
else:
    print("None")


S=set(input())
k=0
for i in range(97, 97+26):
    s0=set(chr(i))
    if(not(s0.issubset(S)) and k==0):
        k=chr(i)
        break

if(k!=0):
    print(k)
else:
    print("None")


print((lambda x:"None" if not x else min(x))(set(chr(97+i) for i in range(26))-set(input())))


S = raw_input()
ss = set(S)
ans = set("abcdefghijklmnopqrstuvwxyz").difference(ss)

if len(ans): print(min(ans))
else: print("None")


S = input()
flag = False
for i in range(26):
    c = chr(ord('a')+i)
    if c not in S:
        print(c)
        flag = True
        break
if flag == False:
    print('None')


print((lambda x:"None" if not x else x[0])(sorted(set(chr(97+i) for i in range(26))-set(input()))))


import sys
S = input()
a = 'abcdefghijklmnopqrstuvwxyz'
a = 'abcdefghijklmnopqrstuvwxyz'
for aa in a:
    if aa in S:
        pass
    else:
        print(aa)
        sys.exit()
print('None')


string=raw_input()
allist=['a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z']
ans='None'
for i in range(len(allist)):
    if allist[i] not in string:
        ans=allist[i]
        break
print ans


a = input()

alpha = [chr(i) for i in range(97, 97+26)]

flag = True;
for c in alpha:
    if c not in a:
        print(c)
        flag = False
        break

if flag:
    print("None")


S = input()

for i in range(97, 97 + 26):
    if chr(i) not in S:
        print(chr(i))
        exit()

print('None')


S = input()
check = list("abcdefghijklmnopqrstuvwxyz")

for c in check:
    if not c in S:
        print(c)
        break
else:
    print("None")


bun=input()
mm="abcdefghijklmnopqrstuvwxyz"
for x in range(len(mm)):
    if mm[x] not in bun:
        print(mm[x])
        break
else:
    print("None")


S=input()
ans='None'
for c in range(26):
  if chr(97+c) not in S:
    ans = chr(97+c)
    break
print(ans)


s = raw_input()
for i in range(26):
    c = chr(ord('a')+i)
    if c in s:
        continue
    else:
        print c
        break
else:
    print 'None'


if __name__ == '__main__':
    S = input()
    dic = [chr(i) for i in range(97, 123)]
    j=0
    for i in range(len(dic)):
        if dic[i] not in S:
            j = 1
            print(dic[i])
            break
    if j == 0:
        print('None')


import math,string,itertools,fractions,heapq,collections,re,array,bisect,sys,random,time,copy,functools

sys.setrecursionlimit(10**7)
inf = 10**20
gosa = 1.0 / 10**10
mod = 10**9 + 7

def LI(): return [int(x) for x in sys.stdin.readline().split()]
def LI_(): return [int(x)-1 for x in sys.stdin.readline().split()]
def LF(): return [float(x) for x in sys.stdin.readline().split()]
def LS(): return sys.stdin.readline().split()
def I(): return int(sys.stdin.readline())
def F(): return float(sys.stdin.readline())
def S(): return input()

def main():
    c = collections.Counter(S())
    for k in string.ascii_lowercase:
        if c[k] == 0:
            return k
    return 'None'

print(main())


def main():
    S = input()

    for i in range(97, 123):
        if not chr(i) in S:
            ans = chr(i)
            break
    else:
        ans = 'None'

    print(ans)

main()


a,b=map(int,input().split())
print(a-b if a-b>0 else 0)


#ABC072A

x,t=map(int,raw_input().split())
if x>=t:
 print x-t
else:
 print 0


tmp = input()
X = int(tmp.split()[0])
t = int(tmp.split()[1])
if X - t >= 0:
    print(X - t)
else:
    print(0)


# -*- coding:utf-8 -*-
X, t = map(int, input().split())
if X-t >= 0:
    print(X-t)
else:
    print(0)


X, t=[int(i) for i in input().split()]
if(X-t < 0):
    print(0)
else:
    print(X-t)


nm = input().strip().split(' ')
n = int(nm[0])
m = int(nm[1])

r = n- m

if r < 0:
    r =0
print(r)


X,t=map(int,input().split())
if (X>t):
 print(X-t)
else:
 print(0)


# coding: utf-8
def get_ln_inputs():
    return input().split()

def get_ln_int_inputs():
    return list(map(int, get_ln_inputs()))

def main():
    X, t = get_ln_int_inputs()
    print(max(0, X - t))
    return

main()


x, t = map(int, input().split(" "))

print(max(x-t, 0))


x,t=map(int, input().split())
print(max(0, x-t))


X, t = [int(x) for x in input().split()]

Rest = X - t
if Rest < 0:
  Rest = 0

print(Rest)


i = list(map(int, input().split()))
if i[0] > i[1]:
    print(i[0]-i[1])
else:
    print(0)


X, t = map(int, input().split())
if X <= t:
    print(0)
else:
    print(str(X - t))


Xt = list(map(int,input().split()))
print(max(Xt[0]-Xt[1],0))


x,t = map(int, input().split())
m = max(x-t,0)
print(m)


X, t = input().split()
X, t = int(X),int(t)

res = X -t

if res >= 0:
    print(res)
else:
    print(0)


X, t = [int(x) for x in input().split()]

print(X - t if X >= t else 0)


X, t = map(int, input().split())
if X > t:
    print(X - t)
else:
    print(0)


X, t = map(int, input().split(' '))
ans = X - t
if ans < 0:
    ans = 0
print(ans)


x , t = map(int ,input().split() )

if t < x:
  print( x - t )
else:
  print( 0 )


X, t = list(map(int, input().split()))

dif = X - t
if dif < 0:
    print(0)
else:
    print(dif)


x, t = map(int, input().split())
if t > x:
  print(0)
else:
  print(x - t)


x, y = list(map(int, input().split()))
print(x-y if x-y > 0 else 0)


temp = input().split(" ")
suna = int(temp[0])
time = int(temp[1])
ans = suna - time
if ans <= 0:
    ans = 0
print(ans)


x, t = map(int, input().split())
print(x-t if x > t else 0)


def a():
    x, t = map(int, input().split())
    print(max(0, x - t))

a()


# -*- coding: utf-8 -*-

x, t = list(map(int, input().split()))
print(x - t) if x - t >= 0 else print(0)


def read(): return list(map(int, input().split()))

x, t = read()
print(max(0, x - t))


X, t = map(int, input().split())
print(max(0, X-t))


X,t = map(int, input().split())
if X-t<0:
    print(str(0))
else:
    print(str(X-t))


a, b = map(int, input().split())
print(max(0, a-b))


X, t = map(int, input().split())
if X >= t:
    print(X - t)
else:
    print(0)


import numpy as np
x, t = map(int, input().split())
print(max(x-t, 0))


X,t = map(int, input().split())

ans = X-t
if ans < 0:
    ans = 0

print(str(ans))


def hourglass():
    X, t = list(map(int, input().split(" ")))
    if X - t <= 0:
        print(0)
    else:
        print(X - t)

hourglass()


X, t = map(int, input().split())		# 5 7

print( max(0, X-t) )


def main():
    X, t = map(int, input().split())
    print(max(X - t, 0))

if __name__ == '__main__':
    main()


X, t = map(int, input().split())
print(max(0, X - t))


X,t=list(map(int,raw_input().split()))

if X-t>=0:
	print X-t
elif X-t<0:
	print 0


X, t = map(int,input().split())
print(max(0, X-t))


X,t = [int(i) for i in input().split()]
print(max(X-t,0))


#!usr/bim/python
#! -*- coding: utf-8 -*-

xg = raw_input()
xg = xg.split()
x,g = map(int,xg)

ans = x-g

if ans < 0:
    ans = 0

print ans


if __name__ == '__main__':
    x, t = list(map(int, input().split(" ")))
    print(max(0, x - t))


X,t = map(int,input().split(" "))

if X-t>0:
    print(X-t)
else:
    print(0)


# -*- coding: utf-8 -*-
"""

"""

if __name__ == '__main__':
    start, elapse = [int(x) for x in input().split(' ')]
    if elapse > start:
        print('0')
    else:
        print('{}'.format(start - elapse))


X, t = list(map(int, input().split()))
print(max(0, X - t))


x,t=map(int,input().split())
if x>= t:
    print(x-t)
else:
    print(0)


if __name__ == '__main__':
    X, t = [int(i) for i in input().split()]
    if X - t < 0:
        print(0)
    else:
        print(X - t)


import sys

def main():
    X, t = list(map(int, input().split()))
    if X - t >= 0:
        print(X - t)
    else:
        print(0)

if __name__ == '__main__':
    main()


xt = list(map(int,input().split()))
if xt[0] > xt[1]:
    print(xt[0]-xt[1])
else:
    print(0)


a, b = map(int, input().split())
print(max(0, a - b))


i, j = map(int, input().split(" "))
print(i-j if i >= j else 0)


x,t = map(int, raw_input().split())
print max(0, x-t)


X, t = map(int, input().split())
if X > t:
    print(X - t)
else:
    print(0)


from sys import stdin
n,x = map(int,stdin.readline().split())
print max(0,n-x)


X,t =map(int,input().split())
if X >= t:
    print(X-t)
else:
    print(0)


X,t=map(int,raw_input().split(' '))

r=X-t

if r<0:
    print 0
else:
    print r


def solve():
    X, t = list(map(int, input().split(" ")))
    if X - t <= 0:
        print(0)
    else:
        print(X - t)

solve()


X,t=map(int,input().split())
print(X-t) if X-t>0 else print(0)


x,t = map(int,input().split())
ans = x - t
if ans > 0:
    print(ans)
else:
    print("0")


if __name__ == '__main__':
    X, t = map(int, input().split())
    re = X-t
    if re>0:
        print(re)
    else:
        print(0)


x, t = map(int, input().split())

print(max(x - t, 0))


x,t = map(int,raw_input().split())
if x < t:
    print 0
else:
    print x - t


X, t = map(int, input().split())
print(max(0, X-t))


x,y=map(int, input().split())
print(x-y if x-y>=0 else 0)


X, t = [int(x) for x in input().split()]
if X<=t :
    print(0)
else :
    print(X-t)


l = list(map(int, input().split()))
a1=l[0]-l[1]
if a1>0:
    print(a1)
else:
    print(0)


a, b = map(int,input().split())
if a >= b : print (a-b)
else : print (0)


a, t = map(int, raw_input().split())
if t >= a:
    print(0)
else:
    print(a-t)


xt=input().split()
x=int(xt[0])
t=int(xt[1])
ans=x-t
if ans<0:
    ans=0
print(ans)


import numpy as np
x, t = map(int, input().split())
print(np.max(np.array([x-t, 0])))


x,t=map(int, input().split())
print(max(x-t, 0))


X, t = list(map(int, input().split(' ')))
print(X - t if (X - t) >= 0 else 0)


# problem A
X, t = map(int, input().split())
if X-t > 0:
    print(X-t)
else:
    print(0)


X, t = list(map(int, input().split()))
print(max(0, X-t))


import os
a,b = os.read(0,100).split(b' ')
a = int(a.decode())
b = int(b.decode())
print(max(a-b,0))


x, t = list(map(int, input().split()))
print(max((x - t), 0))


x = input().split()
a = int(x[0])
b = int(x[1])
c = a-b
if a <= b:
 print("0")
else:
 print(c)


x, t = (int(i) for i in input().split())
ans = x-t
if ans < 0:
    ans = 0
print(ans)


a =  map(int, raw_input().strip().split())
ans = a[0] - a[1]
if ans > 0:
	print(ans)
else:
	print('0')


myinput=input()
X,t=map(int,myinput.split())
if X<t:
    print(0)
else:
    print(X-t)


# encoding: "utf-8"

class Stdin:
    @staticmethod
    def read_line(converter=str):
        return [converter(x) for x in input().split()]

    @staticmethod
    def read_lines(n, converter=str):
        result = list()
        for _ in range(n):
            result.append(Stdin.read_line(converter))
        return result

    @staticmethod
    def convert(data, converter):
        assert(len(data) == len(converter))
        return tuple(map(lambda x, f: f(x), data, converter))

    @staticmethod
    def convert_lines(datas, n, converter):
        return [converter(data, n, converter) for data in datas]

def main():
    x, t = Stdin.read_line(converter=int)
    r = x - t
    if r < 0:
        r = 0
    print(r)

if __name__ == "__main__":
    main()


xtstr = input().split()
x, t = int(xtstr[0]),  int(xtstr[1])
if x >= t:
    print(x-t)
else:
    print('0')


X, t = map(int, input().split())
diff = X-t
if diff > 0:
  print (diff)
else:
  print (0)


a = map( int, raw_input().split(' '))
if (a[0] - a[1] >= 0):
	print a[0] - a[1]
else:
	print 0


x, t = (int(i) for i in input().split())
if x-t<0:
    print(0)
else:
    print(x-t)


X, t = map(int, input().split())

if X-t>=0:
    print(X-t)
else:
    print("0")


def solve():
    X, t = map(int, input().split())
    if (X-t) < 0:
        print(0)
    else:
        print(X-t)

if __name__ == '__main__':
    solve()


X, t = map(int, input().split())

res = max(0, X-t)
print(res)


X, t = map(int, input().split())
if X <= t:
	print('0')
else:
	print(X-t)


X, t = map(int, input().split())

g = X - t

if g >= 0:
    print(g)
else:
    print(0)


X, t = map(int, input().split())
if X>t:
    print(X - t)
else:
    print(0)


x,t = map(int,input().split())
print(max(0,x-t))


#ABC072A

x,t=map(int,raw_input().split())
if x-t>0:
 print x-t
else:
 print 0


a,b = map(int, input().split())
c=a-b
if c>=0:
    print(c)
else:
    print(0)


X, t = map(int, input().split())
print(X - t if X - t > 0 else 0)


a, b = map(int, input().split())
print(max(0, a - b))


from collections import defaultdict
from itertools import product, groupby
from math import pi
from collections import deque
from bisect import bisect, bisect_left, bisect_right
INF = 10 ** 10

def main():
    X, t = map(int, input().split())
    print(max(0, X - t))

if __name__ == '__main__':
    main()


x,t = map(int, input().split())
if x -t > 0:
    print(x-t)
else:
    print(0)


X, t = map(int, input().split())
Y = max(0, X - t)
print(Y)


# -*- encoding: utf-8 -*-
x, t = map(int, input().rstrip().split(' '))

print(max(0, x - 1 * t))


def main():
    x, t = map(int, input().split())

    if t < x: print(x-t)
    else: print(0)

if __name__ == "__main__":
    main()


i, j = [int(i) for i in input().split()]
print(i-j) if j < i else print(0)


#砂時計の砂X(秒)をセット #測った時間tをセット
X , t = map(int,input().split())
#残り時間を表示 (X - t)
#X > tのとき
if X > t:
    time = X - t
#X <= tのとき
else:
    time = 0
print(time)


X, t = map(int, input().split())
print(max(0, X - t))


X, t = list(map(int, input().split()))

print(max(X - t, 0))


def main():
    X, t = [int(i) for i in input().split()]
    #print(X)
    #print(t)

    ans = X - t

    if(ans < 0):
        ans = 0

    print(ans)

if __name__=="__main__":
    main()


X, t = map(int, raw_input().split())
print max(X - t, 0)


X, t = map(int, input().split())

if t <= X:
    print(X - t)
else:
    print(0)


#!/usr/bin/env python

X,t=map(int,input().split())
if t>X:
    ans=0
else:
    ans=X-t

print(ans)


n, m = map(int, input().split())
x = n - m
if x <= 0:
    x = 0
print(x)


l = input().split()
x = int(l[0])
t = int(l[1])
y = x - t
if y > 0:
	print('{0}'.format(y))
else:
	print('0')


import sys

a = map(int,raw_input().strip().split(" "))

result = a[0] - a[1]

if result >= 0:
    print result
else:
    print 0


a,b=map(int,raw_input().split())
print a-b if a>b else 0


print(max(0, (lambda x:x[0]-x[1])([int(i) for i
             in input().split()])))


X ,t=map(int,input().split())

if X-t>0:
    print(X-t)
else:
    print(0)


import math,string,itertools,fractions,heapq,collections,re,array,bisect,sys,random,time,copy,functools

sys.setrecursionlimit(10**7)
inf = 10**20
eps = 1.0 / 10**10
mod = 10**9+7

def LI(): return [int(x) for x in sys.stdin.readline().split()]
def LI_(): return [int(x)-1 for x in sys.stdin.readline().split()]
def LF(): return [float(x) for x in sys.stdin.readline().split()]
def LS(): return sys.stdin.readline().split()
def I(): return int(sys.stdin.readline())
def F(): return float(sys.stdin.readline())
def S(): return input()

def main():
    x,t = LI()

    return max(x-t,0)

print(main())


import os
a,b = os.read(0,100).split(b' ')
a = int(a.decode())
b = int(b.decode())
os.write(1,str(max(a-b,0)).encode())


def A_Sandglass2(X, t):
    return max(X - t, 0)

X,t = [int(i) for i in input().split()]
print(A_Sandglass2(X, t))


X, t = map(int, raw_input().split())
print max(X-t, 0)


tmp=map(int, raw_input().split(" "))
if tmp[0]<tmp[1]:
    print 0
else:
    print tmp[0]-tmp[1]


s = input()
s2 = ''
for i in range(len(s)):
    if (i % 2 == 0):
        s2 += s[i]

print(s2)


s = input()
t = len(s)
for i in range(0,t,2) :
    print (s[i] , end='')


s=input()
l=[x for x in s[::2]]
print("".join(l))


s = input()
o = ""
for i, ss in enumerate(s):
    if i % 2 == 0:
        o = o + ss
print(o)


s = input()
for i in range(len(s)):
    if i % 2 == 0:
        print(s[i], end="")
print("")


def main():
    S =  input()
    #print(S)
    #print(S[1])
    #print(t)

    string = "".join( [S[i] for i in range(0, len(S), 2)] )
    print(string)

if __name__=="__main__":
    main()


s = raw_input()
print "".join(s[i] for i in xrange(len(s)) if i%2 == 0)


print("".join([j for i,j in enumerate(input()) if i%2==0]))


#coding:utf-8

string = input()

res = ""
for i, char in enumerate(string):
    if i % 2 == 0:
        res += char
print (res)


s = input()
t = len(s)
for i in range(0,t,2) :
    print (s[i] , end='')

print()


def main():
    print(input()[::2])

if __name__ == '__main__':
    main()


s = input()
for i, e in enumerate(s):
    if i % 2 == 0:
        print(e, end="")
print("")


import sys

# sys.stdin = open('b1.in')

def read_int_list():
    return list(map(int, input().split()))

def read_str_list():
    return input().split()

def read_int():
    return int(input())

def read_str():
    return input()

def main():
    s = read_str()
    res = s[0::2]
    print(res)

main()


s = input()
for i in range(0, len(s), 2):
    print(s[i], end='')
print()


import sys

S = raw_input()

S_len=len(S)

if(S_len%2==0):
    S_len=S_len/2
elif(S_len%2>0):
    S_len=S_len/2+1

list=''
for i in range(S_len):
    i=i*2
    list+=S[i]

print list


def B_OddString(s):
    ans = ''
    for i in range(len(s)):
        if i % 2 == 0:
            ans += s[i]
    return ans

s = input()
print(B_OddString(s))


def oddOut():
    s = str(input())
    print(s[::2])
oddOut()


def b():
    s = input()
    print(s[::2])

b()


s = input()
a = ""

for i in range(0,len(s),2):
    a = a+s[i]

print(a)


s = input()
ss = [s_ for idx, s_ in enumerate(list(s)) if idx % 2 == 0]
print(''.join(ss))


s = input()

for i , t in enumerate(s):
  if i%2 == 0:
    print(t,end = "")
print()


from sys import stdin
a = stdin.readline().strip()
ans = ""
l = len(a)
for i in xrange(l):
 if i%2==0:
  ans += a[i]
print ans


n = list(input())
for i in range(len(n)):
    if i%2 == 0: print(n[i],end="")
print()


s = input()
print(''.join([c for i, c in enumerate(s) if i % 2 == 0]))


tmp=map(str, raw_input())

arr=[]
for n,i in enumerate(tmp):
    if n%2==0:
        arr.append(i)

print "".join(arr)


S = input()
ans = ""

for i in range(0, len(S), 2):
    ans += S[i]

print(ans)


#!/usr/bin/env python3
# -*- coding: utf-8 -*-

def main():
    S = input()
    print(S[::2])

if __name__ == "__main__": main()


s=input()
ans=''
for i in range(0, len(s), 2) :
    ans+=s[i]
print(ans)


s = input()
ans = ''
count = 0
while True:
    ans += s[count]
    count += 1
    if len(s) == count:
        break
    count += 1
    if len(s) == count:
        break

print(ans)


s = raw_input()

ans = ""

for i in range(len(s)):
    if ((i + 1) % 2) != 0:
        ans += s[i]

print ans


# coding: utf-8
# Here your code !
str =""
i =1
for j in input():
    if i%2==1:
        str+=j
    i+=1
print(str)


# problem B
s = input()
n = len(s)

out = ""
for i in range(0, n, 2):
    out += s[i]
print(out)


import sys
a = sys.stdin.readline().strip()
print (a[::2])


a=raw_input()
b=list(a)
c=1
ans=""
for i in b:
  if c%2==1:
    ans+=i
  c+=1
print ans


S = input()

res = ""

for i, v in enumerate(S):
    if i % 2 == 0:
        res += v

print(res)


s = input()
ans = ""
n = len(s)
for i in range(len(s)):
    if i % 2 == 0:
        ans = ans + s[i]
print(ans)


a = raw_input()
s = ""
for i in range(0, len(a), 2 ):
	s = s + a[i]
print s


s = input()
l = []
for i in range(len(s)):
    if i % 2 == 0:
        l.append(s[i])

print(''.join(l))


temp = input().split(" ")
mojis = list(temp[0])
ans = ""
for a in range(len(mojis)):
    if a % 2 == 0:
        ans = ans + mojis[a]
print(ans)


S = input()
t = ""
for i in range(0, len(S), 2):
  t = t + S[i]

print(t)


# coding: utf-8
def get_ln_inputs():
    return input().split()

def get_ln_int_inputs():
    return list(map(int, get_ln_inputs()))

def main():
    print(get_ln_inputs()[0][::2])

main()


st=input()
s=""
for i in range(0,len(st)):
    if i % 2 ==0:
        s+=str(st[i])
    else:
        pass
print(s)


if __name__ == '__main__':
    STR = input()
    ans = ''
    for i in range(0, STR.__len__(), 2):
        ans += STR[i:i+1]
    print(ans)


def main():
    S = input()
    print(S[::2])

main()


def main():
    print(''.join([c for c in input()[::2]]))

if __name__ == "__main__":
    main()


word = input()

answer = ''

for i in range(0, len(word), 2):
    answer += word[i]

print(answer)


s=input()
r=""
for i in range(len(s)):
    if i%2==0:
        r+=s[i]
print(r)


s = input()
for i in range(0, len(s), 2):
	print(s[i], end = '')


S = input()
d = ""

for i, s in enumerate(S):
    if i%2 == 0:
        d += s

print(d)


s = input()
ans = ''
for i in range(len(s)):
    if i % 2 == 0:
        ans += s[i]
print(ans)


print "".join(map(str, [c for i,c in enumerate(raw_input()) if i % 2 == 0]))


s = input()
l = len(s)
for i in range(l):
  if i % 2 == 0:
    print(s[i], end='')


import sys

def main():
    S = sys.stdin.readline()[:-1]
    print(S[::2])

if __name__ == '__main__':
    main()


def read_line(*types): return [f(a) for a, f in zip(input().split(), types)]

s, = read_line(str)

for i in range(len(s)):
    if i % 2 == 0:
        print(s[i], end='')


s = input()
result = ""
for i in range(0, len(s), 2):
    result += s[i]

print(result)


# -*- coding: utf-8 -*-
"""

"""

if __name__ == '__main__':
    txt = input()
    result = txt[::2]
    print(result)


s = input()
l = len(s)
ans = []
for i in range(l):
    if i % 2 == 0:
        ans.append(s[i])
s = "".join(ans)
print(s)


s = input()
ans = ""
for i in range(len(s)):
  if(i % 2 == 0):
    ans = ans + s[i]

print(ans)


S = input()

result = ""

for i in range(len(S)):
    if i % 2 == 0:
        result += S[i]

print(result)


s=input()
for i in range(len(s)):
    if i%2==0:print(s[i],end="")


input_line1 = raw_input()
extract1 = input_line1[::2]
print(extract1)


S = input()
arr = []
for i in range(len(S)):
    if i%2 == 0:
        arr.append(S[i])
print(''.join(arr))


# coding: utf-8
s = raw_input()
print s[0::2]


# -*- coding:utf-8 -*-
s = list(input())
a = [ s[tmp] for tmp in range(len(s)) if tmp%2 == 0 ]
print(''.join(a))


s = input()
ans = ""
for i in range(0, len(s), 2):
    ans += s[i]
print(ans)


s = list(input())
n = len(s)
ans = ""
for i in range(0, n, 2):
    ans += s[i]
print(ans)


s = input()
ans = ""
for i in range(0,len(s),2):
    ans += s[i]
print(ans)


s = input()
for i in range(0, len(s), 2):
    print(s[i], end='')
print()


import sys

word = raw_input()
odd = ''
index = 1

for letter in word:
    if (index % 2) != 0:
        odd += letter
    index += 1

print odd


#文字列を読み込む
str = input()
#文字列から奇数文字を取り出す
kisuu_str = ""
for i in range(0,len(str),2):
    kisuu_str += str[i]
#奇数文字のみを表示する
print(kisuu_str)


s = input()
t = 0
for i,j in enumerate(s):
   if i % 2 == 0:
      print(s[i],end="")


def main():
    print(''.join([c for c in input()[::2]]))

if __name__ == "__main__":
    main()


s = input()
t = [s[i] for i in range(0, len(s), 2)]
print(''.join(t))


s = input()
for i in range(len(s)):
    if (i % 2) == 0:
        print(s[i], end="")
print()


s = input()
hoge =list(s)

moji = ''

for num in range(len(s)):
    if num%2 == 0:
        moji += hoge[num]
    continue

print(moji)


# -*- coding: utf-8 -*-

print(input()[::2])


s=list(raw_input())

A=''
for i in range(len(s)):
	if i%2==0:
		A+=s[i]

print A


# -*- encoding: utf-8 -*-
s = input().rstrip()

print(s[::2])


a=input()
count = 1
li=[]
for char in list(a):
    if count % 2 != 0:
        li.append(char)
        count+=1
    else:
        count+=1
b="".join(li)
print(b)


def solve():
    s = input()
    S = s[::2]
    print(S)

if __name__ == '__main__':
    solve()


s = list(input())

for i in range(len(s)):
    if i%2==0:
        print(s[i],end='')

print()


st = str(input())
result = [st[i] for i in range(len(st)) if i%2 == 0]
print("".join(result))


s=input()
for i in range(len(s)):
    if i%2==0:
        print(s[i],end="")
print()


from collections import defaultdict
from itertools import product, groupby
from math import pi
from collections import deque
from bisect import bisect, bisect_left, bisect_right
INF = 10 ** 10

def main():
    s = input()
    print(s[::2])

if __name__ == '__main__':
    main()


#!/usr/bin/python

import sys

def main(argv):
    for line in sys.stdin:
        output = []
        for i, c in enumerate(line.rstrip("\n")):
            if i % 2 == 0:
                output.append(c)
        print("".join(output))

if __name__ == "__main__":
    main(sys.argv)


s = input()

for i,c in enumerate(s):
  if i % 2 == 0:
    print(c, end="")


s = input().strip()
for i, c in enumerate(s):
  if i%2 == 0:
    print(c,end='')
print()


#!usr/bim/python
#! -*- coding: utf-8 -*-

s = raw_input()

ans = ""

i = 0
for i in range(len(s)):
    if i % 2 == 1:
        pass
    else:
        ans += s[i]

print ans


# encoding: "utf-8"

class Stdin:
    @staticmethod
    def read_line(converter=str):
        return [converter(x) for x in input().split()]

    @staticmethod
    def read_lines(n, converter=str):
        result = list()
        for _ in range(n):
            result.append(Stdin.read_line(converter))
        return result

    @staticmethod
    def convert(data, converter):
        assert(len(data) == len(converter))
        return tuple(map(lambda x, f: f(x), data, converter))

    @staticmethod
    def convert_lines(datas, n, converter):
        return [converter(data, n, converter) for data in datas]

def main():
    s = input()
    r = "".join([c for (i,c) in enumerate(s) if i % 2 == 0])
    print(r)

if __name__ == "__main__":
    main()


#ABC072B

s=raw_input()
res=''
for i in xrange(len(s)):
 if i%2==0:
  res+=s[i]
print res


def solve():
    s = list(input())
    s_odd = s[::2]
    print("".join(s_odd))

solve()


a = input()
if a[0] == '9'or a[1] == '9':
	print("Yes")
else: print("No")


def main():
    n = input()
    if '9' in n:
        print('Yes')
    else:
        print('No')

if __name__ == '__main__':
    main()


s=input()
print("Yes" if s/10==9 or s%10==9 else "No")


def main():
    N = int(input())

    N_10 = N//10
    N_1 = N - N_10*10

    if N_10==9:
        print('Yes')
    elif N_1==9:
        print('Yes')
    else:
        print('No')

if __name__=='__main__':
    main()


s=list(input())
for c in s:
    if c=='9':
        print('Yes')
        break
else:
    print('No')


n = input()
if '9' in n:
  print('Yes')
else:
  print('No')


N = int(input())
n10 = N//10
n1 = N%10
if n10 == 9 or n1 == 9:
    print("Yes")
else:
    print("No")


s = input()						# 5

if '9' in s:
	print('Yes')
else:
	print('No')


N = input()
print('Yes' if '9' in N else 'No')


n = raw_input()

l = [int(x) for x in list(str(n))]
if l[0] == 9:
	print("Yes")
elif l[1] == 9:
	print("Yes")
else:
	print("No")


s = input()
if '9' in s:
    print('Yes')
else:
    print('No')


# coding: utf-8

def main():
    n = raw_input()
    for i in n:
        if i == "9":
            print "Yes"
            return
    print "No"

main()


N= int(input())
n=[]
j=9
c=0
while N!=0:
    n.append(N%10)
    N//=10
n.reverse()

for i in range(len(n)):
    if n[i-1]==j:
        c+=1

if c > 0:
    print("Yes")
else:
    print("No")


print "Yes" if "9" in raw_input() else "No"


import numpy as np
hoge = input()
hoge = int(hoge)
if hoge//10 == 9 or hoge%10 == 9:
    print("Yes")
else:
    print("No")


temp = input()
temp = list(temp)
if(temp[0] == "9" or temp[1] == "9"):
    print("Yes")
else:
    print("No")


N=input()
if '9' in (N):
 print('Yes')
else:
 print('No')


N = input()
if N[0] == '9' or N[1] =='9':
    print('Yes')
else:
    print('No')


# coding: utf-8

print("Yes" if '9' in input() else "No")


n = input()
print("Yes") if n.count('9') else print("No")


print 'Yes' if '9' in raw_input() else 'No'


n = list(input())
if '9' in n:
    print("Yes")
else:
    print("No")


N = list(input())

flag = False
if N[0] == "9":
    flag = True
if N[1] == "9":
    flag = True

if flag:
    print("Yes")
else:
    print("No")


n = str(input())

if "9" in n:
    print("Yes")
else:
    print("No")


print('Yes' if '9' in input() else 'No')


N = int(input())
if N % 10==9 or N >=90 :
    print("Yes")
else:
    print("No")


n = input()
print("Yes" if n[0]=='9' or n[1]=='9' else "No")


# coding: utf-8
# Here your code !
n = input()
if n.find('9') >= 0:
    print('Yes')
else:
    print('No')


if "9" in input():
    print("Yes")
else:
    print("No")


if input().find('9')!=-1:
    print("Yes")
else:
    print("No")


N = input()

if N.find("9") != -1:
  print("Yes")
else:
  print("No")


def main():
    N = input()

    if '9' in N:
        print('Yes')
    else:
        print('No')

main()


print("Yes" if "9" in input() else "No")


#!/usr/bin/python

import sys

def main(argv):
    for line in sys.stdin:
        if "9" in line:
            print("Yes")
        else:
            print("No")

if __name__ == "__main__":
    main(sys.argv)


N = int(input())
if N%10 == 9 or N // 10 == 9:
  print("Yes")
else:
  print("No")


import numpy as np

def getInput():
    """

    :return: list of list of str. 1st dim: row, 2nd dim: column.
    """
    separator = ' '
    ret_array = []
    while True:
        try:
            row = input().split(sep=separator)
            ret_array.append(row)
        except EOFError:
            break
    return ret_array

g = getInput()

# number
p = np.array(list(map(int, g[0])), dtype=np.int32)
h, f = divmod(p, 10)
if h == 9 or f == 9:
    print('Yes')
else:
    print('No')


N = input()
if "9" in N:
    print("Yes")
else:
    print("No")


# -*- coding:utf-8 -*-
import sys
N = list(input())
for tmp in N:
    if tmp == '9':
        print("Yes")
        sys.exit()
    else:
        pass
print("No")


print('Yes') if '9' in input() else print('No')


n = input()

if '9' in n:
    print('Yes')
else:
    print('No')


if "9" in input():
  print("Yes")
else:
  print("No")


print("Yes" if '9' in input() else "No")


N = int(input())

if N%10 == 9:
    print('Yes')
elif N >= 90:
    print('Yes')
else:
    print('No')


z=input()
if z[0]=='9' or z[1]=='9':
    print("Yes")
else:print("No")


N = input()
result = "No"
for i in N:
    if i == '9':
        result = "Yes"
print(result)


N = str(input())

if '9' in N:
    flag = 'Yes'
else:
    flag = 'No'

print(flag)


n=str(input())
if '9' in n:
    print('Yes')
else:
    print('No')


n = raw_input()

index = n.find("9")

if index >= 0:
    print "Yes"
else:
    print "No"


num = input()
num = str(num)
isthere = False
for i in range(0, 2):
	if num[i] == '9':
		isthere = True

if isthere:
	print('Yes')
else:
	print('No')


N=input()
if N[0]=="9" or N[1]=="9":
    p="Yes"
else:
    p="No"
print(p)


number = int(raw_input())

if number < 10 and number == 9:
    print 'Yes'
elif (number % 10) == 9:
    print 'Yes'
elif (number / 10) == 9:
    print 'Yes'
else:
    print 'No'


print('Yes' if '9' in input() else 'No')


N = input()

if N%10 == 9:
	print('Yes')
elif N/10 == 9:
	print('Yes')
else :
	print('No')


s = input().strip()
if s[0] == '9' or s[1] == '9':
  print('Yes')
else:
  print('No')


from collections import defaultdict
from itertools import product, groupby
from math import pi
from collections import deque
from bisect import bisect, bisect_left, bisect_right
INF = 10 ** 10

def main():
    N = input()
    print("Yes" if "9" in N else "No")

if __name__ == '__main__':
    main()


N = input()

print("Yes" if "9" in N else "No")


s = input()
print("Yes" if '9' in s else "No")


n=int(input())

if  (n>89) or (n%10==9):
    print('Yes')
else:
    print('No')


a = list(input())
if "9" in a:
    print("Yes")
else:
    print("No")


import sys

N = int(sys.stdin.readline())
n1 = N % 10
n2 = int((N - n1) / 10)

if n1 == 9 or n2 == 9:
    print('Yes')
else:
    print('No')


if '9' in input():
 print('Yes')
else:
  print('No')


a = input()
if '9' in a:
    print("Yes")
else:
    print("No")


inp = input()

if '9' in inp:
  print('Yes')
else:
  print('No')


# -*- coding: utf-8 -*-
import heapq
import math

a = input()
b = False
for aa in a:
    if aa == '9':
        b = True
print('Yes' if b else 'No')


N = input()

if "9" in N:
    print("Yes")
else:
    print("No")


n=list(str(input()))
for x in n:
    if x=="9":
        print("Yes")
        break
else:
    print("No")


N = input()
if "9" in N:
    print("Yes")
else:
    print("No")


n = input()
if n[0]=='9' or n[1]=='9':
    print('Yes')
else:
    print('No')


n=input()
s="No"
for i in range(len(n)):
    if n[i]=="9":
        s="Yes"
print(s)


num = int(input())
if num % 10 == 9 or num // 10 == 9:
    print("Yes")
else:
    print("No")


N = input()

for i in range(len(N)):
    if N[i] == "9":
        print("Yes")
        exit()

print("No")


N = input()
print('Yes' if '9' in N else 'No')


n = int(input())
if n%10==9 or n//10==9:
    print('Yes')
else :
    print('No')


print("Yes" if ("9" in list(input())) else "No")


s=input()
print('Yes' if '9' in s else 'No')


print('Yes' if '9' in input() else 'No')


N = int(input())

if N // 10 == 9 or N % 10 == 9:
    print("Yes")
else:
    print("No")


def A_September(N):
    if '9' in N:
        return 'Yes'
    else:
        return 'No'

N = input()
print(A_September(N))


if '9' in input():
    print('Yes')
else:
    print('No')


n = input()
if "9" in n:
    print("Yes")
else:
    print("No")


N = input()

if "9"in N:
    print("Yes")
else:
    print("No")


n = input()
if '9' in n:
  print('Yes')
else:
  print('No')


a=raw_input()

a = int (a)

if a%10==9:
    print "Yes"
elif (a/10)%10==9:
    print "Yes"
else :
    print "No"


#!/usr/bin/env python3
# -*- coding: utf-8 -*-

def main():
    s = input()
    print("Yes" if "9" in s else "No")

if __name__ == "__main__": main()


number = input()
if '9' in number:
    print('Yes')
else:
    print('No')


N = input()
try:
  N.index('9')
  print('Yes')
except:
  print('No')


input = int(input())

first_digit = input % 10
second_digit = int((input - first_digit) / 10)

if first_digit == 9 or second_digit == 9:
    print("Yes")
else:
    print("No")


a=list(str(input()))
ch=0
for i in a:
    if i=="9":
        ch=1
if ch==1:
    print "Yes"
else:
    print "No"


N = input()
if "9" in N:
    print("Yes")
else:
    print("No")


a = input()
b = int(a[0])
c = int(a[1])
if b==9 or c==9:
 print("Yes")
else:
 print("No")


N = int(raw_input())
print 'Yes' if '9' in str(N) else 'No'


import sys

# sys.stdin = open('a1.in')

def read_int_list():
    return list(map(int, input().split()))

def read_str_list():
    return input().split()

def read_int():
    return int(input())

def read_str():
    return input()

def main():
    n = read_int()
    l = [9, 19, 29, 39, 49, 59, 69, 79, 89, 99, 98, 97, 96, 95, 94, 93, 92, 91, 90]
    if n in l:
        print('Yes')
    else:
        print('No')

main()


N=input()
print "Yes" if N%10==9 or N/10==9 else "No"


n = input()

if n[0] == '9' or n[1] == '9':
        print("Yes")
else:
        print("No")


n = input()

check = 0
for i in n:
    if i == "9":
        check = 1
        break

if check == 1:
    print("Yes")
else:
    print("No")


s = input()
if '9' in s:
    print('Yes')
else:
    print('No')


#! /bin/python
# coding:utf-8

import itertools

N = raw_input()

if (N.find('9') == -1):
    print "No"
else:
    print "Yes"


s = input()
print('Yes') if '9' in s else print('No')


import collections

# デバッグ用
DEBUG = False
# DEBUG = True

# 宣言
result = 'No'

# 入力部
if DEBUG:
    N = '99'
else:
    N = input()

# 処理部
if N.find('9') >= 0:
    result = 'Yes'
else:
    result = 'No'

# 出力部
print(result)


N = input()

if N[0] == '9' or N[1] == '9':
    print('Yes')
else:
    print('No')


n = input()

if n.count('9') > 0:
    print("Yes")
else:
    print("No")


n = int(input())
print("Yes" if n%10==9 or n//10 == 9 else "No")


N = input()
result = "No"
if N[0] == "9":
    result ="Yes"
if N[1] == "9":
    result = "Yes"
print (result)


print ("Yes" if '9' in input() else "No")


x=input()
a="No"
if "9" in x:
  a="Yes"
print(a)


def solution():
	n = int(input())
	print('Yes' if '9' in list(str(n)) else 'No')

solution()


#a = map(int,raw_input().strip().split())
a = raw_input()
p = False
for x in a:
	if x == '9':
		p = True
if p:
	print("Yes")
else:
	print("No")


s = input()

flag = 0
for i in s:
    if i == "9":
        flag = 1

if flag == 1:
    print("Yes")
else:
    print("No")


# A

S = list(input())
if '9' in S:
    print("Yes")
else:
    print("No")


# -*- coding: utf-8 -*-
import math
a = int(input())
if a%10==9 or math.floor(a/10)==9:
    print ("Yes")
else:
    print ("No")


N = input()

if '9' in str(N):
    x = 'Yes'
else:
    x = 'No'

print(x)


x = str(input())

if x[0]=='9' or x[1]=='9':
    print('Yes')
else:
    print('No')


N=str(input())
if N[0]=="9" or N[1]=="9":
  print("Yes")
else:
  print("No")


import math
N=int(input())
if N%10==9 or math.floor(N/10)==9:
  print("Yes")
else:
  print("No")


# -*- coding: utf-8 -*-

import sys

def main():
    for line in sys.stdin:
        if "9" in line.rstrip():
            print("Yes")
        else:
            print("No")

if __name__ == "__main__":
    main()


inn = input()
ans = "No"
if inn[0] == "9":
    ans = "Yes"
if inn[1] == "9":
    ans = "Yes"
print(ans)


s=int(input())
print("Yes" if s//10==9 or s%10==9 else "No")


#coding:utf-8

num = int(input())

if num // 10 == 9 or num % 10 == 9:
    print("Yes")
else:
    print("No")


x = input()
if '9' in x:
    print("Yes")
else :
    print("No")


def solve(s):
    if "9" in s:
        print("Yes")
    else:
        print("No")

if __name__ == '__main__':
    s = input()
    solve(s)


s = input()
pos = s.find('9')
if pos != -1:
    print("Yes")
else:
    print("No")


def solve(): # 073A- September 9
    n = int(input())
    n_10 = n // 10
    n_1 = n - n_10 * 10

    if n_10 == 9 or n_1 == 9:
        print("Yes")
    else:
        print("No")

solve()


n = int(input())

if(n / 90 >= 1 or n % 10 == 9):
    print("Yes")
else:
    print("No")


a = input()
for i in range(len(a)):
   if a[i] == "9":
      print("Yes")
      break
else:
   print("No")


a = input()
if a%10==9 or a/10 ==9:
    print "Yes"
else:
    print "No"


print("Yes" if "9" in input() else "No")


import sys
for i in input():
    if i =='9':
        print("Yes")
        sys.exit()
print("No")


s = input()

if '9' in s:
    print('Yes')
else:
    print('No')


N = int(input())
total = 0
for i in range(N):
    l,r = map(int, input().split())
    total += (r - l + 1)
print(total)


#Theater
N = int(input())
cnt = 0
for i in range(N):
    r,l = list(map(int, input().split()))
    cnt += l-r+1
print(cnt)


def main():
    n = int(input())
    ans = 0
    for _ in range(n):
        a, b = map(int, input().strip().split())
        ans += b - a + 1
    print(ans)

if __name__ == '__main__':
    main()


N = int(input())
Sum = 0
for i in range(N):
    sheet = list(map(int,input().split()))
    Sum += sheet[1] - sheet[0] + 1
print(Sum)


import math,string,itertools,fractions,heapq,collections,re,array,bisect,sys,random,time,copy,functools

sys.setrecursionlimit(10**7)
inf = 10**20
gosa = 1.0 / 10**10
mod = 10**9+7

def LI(): return [int(x) for x in sys.stdin.readline().split()]
def LI_(): return [int(x)-1 for x in sys.stdin.readline().split()]
def LF(): return [float(x) for x in sys.stdin.readline().split()]
def LS(): return sys.stdin.readline().split()
def I(): return int(sys.stdin.readline())
def F(): return float(sys.stdin.readline())
def S(): return input()

def main():
    n = I()
    r = 0
    for _ in range(n):
        a,b = LI()
        r += b-a+1

    return r

print(main())


n = int(input())
p = 0
for _ in range(n):
    l, r = map(int, input().split())
    p += r - l + 1

print(p)


# coding: utf-8
# Here your code !
n = int(input())
ans = 0
for i in range(n):
    l, r = list(map(int, input().split()))
    ans += r - l + 1
print(ans)


N = int(input())
seat = 0
for _ in range(N):
    l,r = map(int,input().split())
    seat += r - l + 1
print(seat)


n = int(input())
a = 0
for _ in range(n):
    l,r = map(int,input().split())
    a += r-l+1
print(a)


time = int(input())
ans = 0
for i in range(time):
    now = input().split()
    ans += int(now[1]) + 1 - int(now[0])
print(ans)


a = int(input())
b = [map(int, input().split()) for x in range(a)]

print(sum(B - A + 1 for A, B in b))


inp = int(input())

sum = 0
for i in range(inp):
	a, b = map(int, input().split())
	sum += b - a + 1
print(sum)


N = int(input())

s = 0

for i in range(N):
    l, r = list(map(int, input().split(" ")))
    s += r - l + 1

print(s)


n = int(input())
ans = 0
for i in range(n):
    x = input()
    a , b = map(int,x.split())
    ans += b - a + 1
print(ans)


a=input()
ans=0
for i in range(a):
    b=map(int,raw_input().split())
    ans+=b[1]-b[0]+1
print ans


N = int(input())
ans = set([])
for i in range(N):
    strs = [int(s) for s in input().split(' ')]
    for j in range(strs[0],strs[1]+1):
        ans.add(j)

print(len(ans))


N = int(input())
seats = []
sum = N
for i in range(N):
    j = list(map(int, input().split()))
    seats.append(j)

for seat in seats:
    sum += seat[1] - seat[0]

print(sum)


def main():
    N = int(input())
    LR = tuple(tuple(map(int, input().split())) for _ in range(N))

    people = 0
    for l, r in LR:
        people += r - l + 1

    print(people)

main()


n = input()

ans = 0
for i in range(n):
    a, b = map(int, raw_input().split())
    ans += b - a + 1

print ans


def solve(): # 073B- Theater
    N = int(input())
    sum_seat = 0

    for _ in range(N):
        l, r = [int(x) for x in input().split(" ")]
        sum_seat += r + 1 - l

    print(sum_seat)

solve()


n = int(input())
ans = 0
for i in range(n):
    l, r = map(int, input().split())
    ans += r - l + 1
print(ans)


N = int(input())
list_seki = []
for i in range(N):
    list_seki.append(list(map(int,input().split())))

count = 0
for j in range(N):
    count += list_seki[j][1]+1-list_seki[j][0]

print(count)


n=int(input())
ans=0
for _ in range(n):
    l,r=map(int,input().split())
    ans+=r-l+1
print(ans)


N = int(input())
a = []
answer = 0
for i in range(N):
	a.append(list(map(int, input().split())))
	answer = answer + a[i][1] - a[i][0] + 1

print(answer)


n = raw_input()

n = int (n)

ans=0

for i in range(0,n):
    a,b=raw_input().split(' ')
    a = int (a)
    b = int (b)
    ans+=b-a;
    ans+=1

print ans


c=[0]*100010
N=int(input())
for _ in range(N):
  a,b=map(int,input().split())
  c[a] += 1
  c[b+1] -= 1
for i in range(len(c)-1):
  c[i+1] += c[i]
print(sum(c))


value = int(input())
people = 0
while True:
	try:
		seat = input()
		if seat:
			string_seat = seat.split()
			seat_list = []
			seat_list = [int(x) for x in (string_seat)]
			people += seat_list[len(seat_list)-1] - seat_list[0]+1
	except EOFError:
		break
# while True:
# 	seat = input()
# 	if seat:
# 		string_seat = seat.split()
# 		seat_list = []
# 		seat_list = [int(x) for x in (string_seat)]
# 		people += aaa(seat_list)
# 	else:
# 		break
print(people)


N = input()
N = int(N)

seats = []

for i in range(N):
    inputs = input().split()
    seats.append([int(inputs[0]), int(inputs[1])])

ans = 0
for i in seats:
    ans += i[1] - i[0] + 1

print(ans)


n = int(input())
ans = 0
for _ in range(n):
    l, r = map(int, input().split())
    ans += r - l + 1
print(ans)


N = int(input())
people_total = 0
for _ in range(N):
  new_input = input()
  l, r = map(int, new_input.split(" "))
  people_total += r - l + 1

print(people_total)


N = int(input())
seat = [0 for i in range(100000+1)]
for i in range(N):
    l, r = [int(i) for i in input().split()]
    for j in range(l, r+1):
        seat[j] = 1
print(sum(seat))


num=int(raw_input())
output=0
for i in range(num):
    tmp=map(int, raw_input().split(" "))
    output+=tmp[1]-tmp[0]+1

print output


count = 0
x = int(input())
for i in range(x):
    l,r = map(int,input().split())
    count += (r-l+1)
print(count)


# -*- coding: utf-8 -*-
"""
"""

def solve(data):
    total = 0
    for b, e in data:
        num = e - b + 1
        total += num
    return total

def main():
    N = int(input())
    data = []
    for _ in range(N):
        data.append([int(x) for x in input().split(' ')])
    result = solve(data)
    print(result)

if __name__ == '__main__':
    main()


def B_Theater(N, C):
    people = 0
    for i in range(0, len(C), 2):
        people += C[i + 1] - C[i] + 1
    return people

N = int(input())
C = [[int(i) for i in input().split()] for i in range(N)]
x = []
for s in C:
    x.extend(s)
C=x
print(B_Theater(N, C))


N = int(input())
sum = 0
for i in range(N):
    i, j = list(map(int, input().split(' ')))
    sum += j - i + 1
print(sum)


z = 0
for _ in xrange(input()):
    (l,r) = map(int,raw_input().split(' '))
    z += r-l+1
print z


#ABC073B

n=int(raw_input())
res=0
for i in xrange(n):
 l,r=map(int,raw_input().split())
 res+=r-l+1
print res


N = int(input())
lr = [list(map(int, input().split())) for n in range(N)]

res = 0
while lr:
    tlr = lr.pop()
    res += tlr[1] - tlr[0] + 1

print(res)


n=int(raw_input())
number=0
while n !=0:
    a ,b=map(int, raw_input().split())
    number+=b-a+1
    n-=1
print(number)


n = int(input())
a = [list(map(int, input().split())) for i in range(n)]
x = 0

for i in range(n):
    x += a[i][1]-a[i][0]+1

print(x)


# B
N = int(input())
res = 0
for _ in range(N):
    l, r = map(int, input().split())
    res += r - l + 1

print(res)


N=int(input())
ans=N
for i in range(N):
  a,b=map(int,input().split())
  ans+=b-a
print(ans)


import sys

def main():
    N = int(input())

    a =[]
    for i in range(N):
        a.append(list(map(int,input().split())))

    count = 0

    for b in a:
        count = count + (b[1]-b[0]+1)

    print(count)

if __name__=='__main__':
    main()


n = int(input())
s = n
for _ in range(n):
  a, b = map(int, input().split(" "))
  s += b - a
print(s)


n=int(raw_input())
res = 0
for i in range(n) :
    x,y = map(int,raw_input().split())
    res += y-x+1
print res


group_num = int(input())
number_of_customer = 0
for _ in range(group_num):
    l = list(map(int, input().split()))
    number_of_customer += l[1] - l[0] + 1
print (number_of_customer)


N = int(input())						# 5

sum=0
for i in range(N):
	l, r = map(int, input().split())		# 5 7
	sum += r - l + 1

print(sum)


N = int(input())
answer = 0
for i in range(N):
	l, r = map(int, input().split())
	answer += r - l + 1
print(answer)


c=[0]*100010
N=int(input())
for _ in range(N):
  a,b=map(int,input().split())
  c[a] += 1
  c[b+1] -= 1
for i in range(len(c)-1):
  c[i+1] += c[i]
print(sum(c))


N = int(input())
num = 0

for i in range(N):
    s, l = map(int, input().split())
    ans = l - s + 1
    num += ans

print(num)


# -*- coding: utf-8 -*-

import sys

def main():
    count = 0
    for line in sys.stdin:
        if len(line.rstrip().split(" ")) == 1:
            continue
        start, end = map(int, line.rstrip().split(" "))
        count += end - start + 1
    print(count)

if __name__ == "__main__":
    main()


a = int(input())
t = 0
for i in range(a):
   b,c = map(int,input().split())
   if b >= c:
      t += (b - c) + 1
   else:
      t += (c - b) + 1
print(t)


# coding: utf-8

N = int(input())

res = 0
for i in range(N):
    l, r = tuple(map(int, input().split()))
    res += r - l + 1

print(res)


n = int(input())
lr_list= []

count =0
for _ in range(n):
#     lr_list.append([int(x) for x in input().split()])
    x, y = [int(x) for x in input().split()]
#     print(x,y)
    count += y-x+1

print(count)


N = int(input())
people = [list(map(int, input().split())) for i in range(N)]
ans = 0

for p in people:
    ans += (p[1] - p[0]) + 1

print(ans)


ans = 0
for i in range(int(input())):
  r1, r2 = input().split()
  ans += int(r2) - int(r1) + 1
print(ans)


N = int(input())

sum = 0
for i in range(N):
    a = list(map(int,input().split()))
    sum += a[1] - a[0] + 1
print(sum)


s = 0
for i in range(int(input())):
    l, r = map(int, input().split())
    s += r - l + 1
print(s)


N = int(input())

ans = 0

for _ in range(N):
    l, r = map(int, input().split())
    ans += r - l + 1

print(ans)


N = input()
ans = 0
for _ in range(N):
    l, r = map(int, raw_input().split())
    ans += r-l+1
print ans


audience = []
total = 0
groups = int(raw_input())

for line in xrange(groups):
    audience.append(raw_input())

for line in audience:
    group = map(int, line.split())
    total += group[1] - group[0] + 1

print total


ans = 0
for i in range(int(input())):
    a,b = map(int,input().split())
    ans += b-a+1
print(ans)


from collections import defaultdict
from itertools import product, groupby
from math import pi
from collections import deque
from bisect import bisect, bisect_left, bisect_right
INF = 10 ** 10

def main():
    N = int(input())
    ans = 0
    for _ in range(N):
        l, r = map(int, input().split())
        ans += r - l + 1
    print(ans)

if __name__ == '__main__':
    main()


# coding: utf-8
# Here your code !
ans = 0
N = int(input())
for i in range(N):
    a , b = map(int,input().split())
    ans = ans + b - a +1
print(ans)


if __name__ == '__main__':
    N = int(input())
    ans = 0
    for i in range(N):
        l = list(map(int, input().split()))
        ans += abs(l[1]-l[0]+1)
    print(ans)


def spaceinput():
    return list(map(int,input().split(" ")))

N=int(input())
l=list()
for i in range(N):
    l.append(spaceinput())

sum=0
for sl in l:
    sum+= sl[1]-sl[0]+1

print(sum)


import sys

# sys.stdin = open('b1.in')

def read_int_list():
    return list(map(int, input().split()))

def read_str_list():
    return input().split()

def read_int():
    return int(input())

def read_str():
    return input()

def main():
    n = read_int()
    res = 0
    for i in range(n):
        l, r = read_int_list()
        r0 = r - l + 1
        res += r0
    print(res)

main()


N = int(input())

sum_num = 0
for i in range(N):
    l, r = map(int, input().split())
    sum_num += r - l + 1

print(sum_num)


N = int(raw_input())
answer = 0
for n in xrange(N):
  l, r = map(int, raw_input().split(' '))
  answer += r - l + 1
print answer


#!/usr/bin/env python
import sys
if __name__ == '__main__':
    line = sys.stdin.readline()
    N = int(line)
    count = 0
    for i in range(N):
    	line = sys.stdin.readline().split(" ")
    	count += int(line[1]) - int(line[0]) + 1
    print(count)


N = int(input())
sum = 0
for i in range(N):
    l, r = map(int, input().split())
    sum += r - l + 1
print(sum)


n=int(input())
x=0
for i in range(n):
  a,b=map(int,input().split())
  x=x+b-a+1
print(x)


n = int(input())
e = [[int(i) for i in input().split()] for i in range(n)]
result = 0
for i in e:
    result += i[1] - i[0]

print(result + n)


#Nをセットする
N = int(input())
people = 0
for i in range(N):
    l,r = map(int,input().split())
    people = people + (r - l + 1)
print(people)


# coding:utf-8

n=int(input())
sum=0
for i in range(0, n):
    l_r=input()
    l=int(l_r.split(" ")[0])
    r=int(l_r.split(" ")[1])
    sum+=r-l+1

print(sum)


N = int(input())
ans = 0
for _ in range(N):
    l, r = map(int, input().split())
    ans += r - l + 1
print(ans)


N=input()
num=0
for i in range(N):
    x=map(int,raw_input().split())
    temp_num=len(range(x[0],x[1]+1))
    num=num+temp_num
print num


N = int(input())
a = [list(map(int, input().split())) for i in range(N)]

ans = 0
for x in a:
  ans += x[1] - x[0] + 1

print(ans)


N = int(input())
a = 0
for i in range(N):
    l, r = map(int, input().split())
    a += r - l + 1
print(a)


n = int(input())
ans = 0
for i in range(n):
    l, r = list(map(int, input().split()))
    ans += r - l + 1

print(ans)


print(sum([1+len(range(*list(map(int,input().split())))) for i in range(int(input()))]))


# coding: utf-8
import sys

def main():

    NumCount = 0

    lines = sys.stdin.readlines()
    for i,line in enumerate(lines):
        if i==0:
            continue
        else:
            value = line.split()
            if len(value)==1:
                NumCount += 1
            else:
                NumCount += int(value[1])-int(value[0]) + 1
    print(NumCount)
    return

if __name__=='__main__':
    main()


N = int(input())
sum = 0
for n in range(N):
    a, b = [int(i) for i in input().split()]
    sum += b-a+1

print(sum)


N=int(input())
ans=N
for i in range(N):
  a,b=map(int,input().split())
  ans+=b-a
print(ans)


N=int(input())
ans=0
for i in range(N):
 l,r=map(int, input().split())
 ans+=r-l+1
print(ans)


N = int(input())
total = 0

for i in range(N):
    group = input().split()
    start, end = int(group[0]), int(group[1])
    total += end - start + 1

print(total)


n = int(input())
print(sum([-int(eval(input().replace(' ', '-')))+1 for i in range(n)]))


n = int(input())
ans = 0
for i in range(n):
    a,b = map(int,input().split())
    ans += (b - a) + 1
print(ans)


N = int(input())

count = 0
for i in range(N):
    inlist = [int(_) for _ in input().split()]
    count += inlist[1] - inlist[0] + 1

print(count)


# -*- coding:utf-8 -*-
N = int(input())
ans = 0
for tmp in range(N):
    l, r = map(int, input().split())
    ans += r-l+1
print(ans)


n = int(input())

sum = 0

for i in range(n):
    l, r = map(int, input().split(" "))

    sum += r - l + 1

print(sum)


N = int(input())

s = 0
for _ in range(N):
    l, r = [int(x) for x in input().split(' ')]
    s += r - l + 1

print(s)


N = int(input())
sum = 0
for i in range(N):
  l, r = [int(n) for n in input().split()]
  sum += r-l+1
print(sum)


n = int(input())
ans = 0
for _ in range(n):
  l, r = map(int, input().split())
  ans += r - l + 1

print(ans)


itera = input()
itera = int(itera)
total = 0

for i in range(0, itera):
	var1, var2 = input().split()
	var1 = int(var1)
	var2 = int(var2)
	total += (var2+1)-var1

print(total)


N=int(input())
people=0
for i in range(N):
    left,right=map(int,input().split())
    number = right - left +1
    people += number
print(people)


N = int(raw_input())
temp = 0
for i in range(0,N):
 a = raw_input().split(" ")
 temp += int(a[1]) - int(a[0])+1
print temp


N = int(input())
X = [list(map(int, input().split())) for _ in range(N)]

ans = 0
for l, r in X:
    ans += r - l + 1
print(ans)


n = int(input())

hito = 0
for i in range(n):
    lr = list(map(int,input().split()))
    hito += (lr[1] - lr[0] +1 )

print(hito)


n = int(input())
p = 0
for _ in range(n):
  i,j = [int(k) for k in input().split()]
  p += j-i+1
print(p)


N = int(input())
L = []
R = []
for i in range(N):
    l, r = list(map(int, input().split()))
    L.append(l)
    R.append(r)
total = 0
for i in range(N):
    total += R[i] - L[i] + 1

print(total)


N = int(input())
ans = 0

for i in range(N):
    a, b = map(int, input().split())
    ans += b-a+1

print(ans)


n = int(input())
ans = 0
for i in range(n):
    l, r = list(map(int, input().split()))
    ans += r - l + 1
print(ans)


N = int(input())
ans = 0
for i in range(N):
    L,R = map(int,input().split())
    ans += R-L +1

print(ans)


n = int(input())
ans = 0
for i in range(n):
    l, r = map(int, input().split())
    ans += r - l + 1
print(ans)


N = int(input())
ans = 0

for i in range(N):
    l, r = map(int, input().split())
    ans += r-l+1

print(ans)


ans = 0
for i in range(input()):
    l, r = map(int, raw_input().split())
    ans += r - l + 1
print ans


N = int(input())
total = 0
for i in range(N):
    l,r = map(int,input().split())
    total += (r - l) + 1
print(total)


#!/usr/bin/python3

n = int(input())

t = 0
for i in range(n):
    c = list(map(int, input().split()))
    t += c[1] - c[0] + 1

print(t)


n = int(input())
ans = 0
for i in range(n):
    l, r = map(int,input().split())
    ans += (r - l + 1)

print(ans)


n=int(input())
ans=0
for i in range(n):
    a,b=map(int,input().split())
    ans += b-a+1

print(ans)


N = int(input())
p = 0
for _ in range(N):
    l, r = map(int, input().split())
    p += r - l +1
print(p)


num = int(input())
ans = 0
for a in range(num):
    temp = input().split(" ")
    for b in range(len(temp)):
        temp[b] = int(temp[b])
    ans += (temp[1] - temp[0]) + 1
print(ans)


N=int(input())

ans=0

for i in range(N):
	a=[int(i) for i in input().split()]
	ans+=(a[1]-a[0]+1)
print(ans)


N = int(input())
total = 0
for i in range(N):
    tmp = list(map(int,input().split()))
    total += tmp[1]-tmp[0]+1
print(total)


N = int(input())
sum = 0

for num in range(N):
	a, b = (int(_) for _ in raw_input().split())
	sum += b - a + 1

print(sum)


N = int(input())

ans = 0
for i in range(N):
    l, r = map(int, input().split())
    ans += r - l + 1

print(ans)


N = input()
ans = 0
for i in xrange(N):
    l, r = map(int, raw_input().split())
    ans += r - l + 1
print ans


N= int(input())

L = []
R = []
for i in range(N):
	l, r= map(int, input().split())
	L.append(l)
	R.append(r)

Q=[]
P=0
for x in range(N):
    P=R[x]-L[x]+1
    Q.append(P)

print(sum(Q))


n = int(input())
ans = 0
for tc in range(n):
  l, r = map(int, input().split())
  ans += (r - l) + 1
print(ans)


N = int(input())
f = lambda l,r: r-l+1
print(sum(f(*map(int,input().split())) for i in range(N)))


n = int(raw_input())
s = 0
for _ in range(n):
    l,r = map(int, raw_input().split())
    s += r - l + 1
print s


sum=0
for i in range(int(input())):
  l,r=[int(x) for x in  input().split()]
  sum = sum + r - l + 1
print(sum)


import numpy as np

def getInput():
    """

    :return: list of list of str. 1st dim: row, 2nd dim: column.
    """
    separator = ' '
    ret_array = []
    while True:
        try:
            row = input().split(sep=separator)
            ret_array.append(row)
        except EOFError:
            break
    return ret_array

g = getInput()

# number
N = np.array(list(map(int, g[0])), dtype=np.int32)
# l,r
l = []
r = []
for row_idx in range(1, len(g)):
    l.append(int(g[row_idx][0]))
    r.append(int(g[row_idx][1]))

l = np.array(l, dtype=np.int32)
r = np.array(r, dtype=np.int32)

s = r-l+1

print(s.sum())


# coding: utf-8

seat = [0] * 100000
n = input()
for _ in xrange(n):
    l, r = map(int, raw_input().split())
    for j in xrange(l-1, r):
        seat[j] = 1

print seat.count(1)


import numpy as np
hoge = input()
N = int(hoge)
data = np.zeros((N,2))
num = 0
for i in range(N):
    hoge = input()
    hoge = hoge.strip().split(" ")
    num += int(hoge[1])-int(hoge[0])+1
print(num)


n = int(input())
ans = 0
for i in range(n):
    a, b = list(map(int, input().split()))
    ans += b - a +1
print(ans)


n = int(input().strip())
total = 0
for _ in range(n):
    l, r = [int(x) for x in input().strip().split()]
    total += r - l + 1
print(total)


N = input()
cus = 0

for i in range(N):
    l = (map(int, raw_input().split()))
    cus += (l[1] - l[0] + 1)

print cus


from collections import Counter
N = int(input())
numbers = [int(input()) for i in range(N)]

num_cnt = Counter(numbers)

ans_box = list(filter(lambda x:x%2==1 , num_cnt.values()))
print(len(ans_box))


def Write_and_Erase():

    numbers = []
    try:
        LOCAL_FLAG
        N = 3
        numbers = [6, 2, 6]
        # N = 4
        # numbers = [2, 5, 5, 2]
        N = 6
        numbers = [12, 22, 16, 22, 18, 12]

    except NameError:
        N = int(input())
        for i in range(N):
            numbers.append(int(input()))

    onPaper = set([numbers[0]])
    for i in range(1, N):
        if numbers[i] in onPaper:
            onPaper.remove(numbers[i])
        else:
            onPaper.add(numbers[i])

    # print(onPaper)
    print(len(onPaper))

Write_and_Erase()


from collections import Counter

def main():
    N = int(input())
    A = []

    for _ in range(N):
        A.append(int(input()))

    ans = 0
    counter = Counter(A)
    for _, cnt in counter.most_common():
        if cnt % 2 == 1:
            ans += 1

    print(ans)

main()


n = int(input())
A = [int(input()) for i in range(n)]

B = set()
for a in A:
    if a in B:
        B.remove(a)
    else:
        B.add(a)
print(len(B))


N = input()
S = set()
for _ in range(N):
    A = input()
    if A in S:
        S.remove(A)
    else:
        S.add(A)
print len(S)


a=input()
b=[]
for i in range(a):
    b.append(input())
b.sort()
c=[]
pre=0
time=0
for i in b:
    if pre==i:
        time+=1
    else:
        if time%2==1:
            c.append(pre)
        pre=i
        time=1
if time%2!=0 and pre!=0:
    c.append(pre)
print len(c)


import numpy as np
N=input()
x=[]
dict={}
for i in range(N):
    a=raw_input()
    if a in dict:
        if dict[a]==1:
            dict[a]=0
        else:
            dict[a]=1
    else:
        dict[a]=1

print np.sum(np.array(dict.values())%2)


d = {}
for i in range(input()):
  a = input()
  d[a] = d.get(a, 0) + 1

print len(filter(lambda x: x % 2, map(lambda x: d[x], d)))


import functools
import collections
n = int(input())
print(sum(
    map(
        lambda x: x % 2,
        functools.reduce(
            lambda d, v: d.update({v: d[v]+1}) or d,
            [int(input()) for i in range(n)],
            collections.defaultdict(lambda: 0),
        ).values(),
    )
))


from collections import Counter

n = int(input())
cnt = Counter(int(input()) for _ in range(n))
print(sum(1 for k, v in cnt.most_common() if v % 2 == 1))


from collections import Counter
print(sum([i % 2 for i in Counter([input() for _ in range(int(input()))]).values()]))


n = int(input())
d = dict()
for i in range(n):
    a = int(input())
    if a in d:
        if d[a] == 0:
            d[a] = 1
        else:
            d[a] = 0
    else:
        d[a] = 1

print(sum(d.values()))


n = int(input())
m = set()
while n:
    x = int(input())
    if x in m:
        m.remove(x)
    else:
        m.add(x)
    n -= 1
print(len(m))


n=int(input())

left=set()
for _ in range(n):
    i=input()
    if i in left:
        left.remove(i)
    else:
        left.add(i)
print(len(left))


# coding=utf-8
N = int(raw_input().rstrip())
A = {}
for i in range(N):
    a = int(raw_input())
    if a in A:
        if A[a] == 1:
            A[a] = 0
        else:
            A[a] = 1
    else:
        A[a] = 1
print sum(A.values())


import sys

stdin = sys.stdin

ni = lambda: int(ns())
na = lambda: list(map(int, stdin.readline().split()))
ns = lambda: stdin.readline()

n = ni()
s = set()
for i in range(n):
    x = ni()
    if x in s:
        s.remove(x)
    else:
        s.add(x)
print(len(s))


# -*- coding: utf-8 -*-
"""
"""

Memo = []
def solve(data):
    global Memo
    for d in data:
        if d in Memo:
            Memo.remove(d)
        else:
            Memo.append(d)
    return len(Memo)

def solve2(data):
    from collections import Counter
    c = Counter(data).most_common()
    remaining = [x for x in c if x[1]%2==1]
    return len(remaining)

def main():
    N = int(input())
    data = [int(input()) for _ in range(N)]
    result = solve2(data)
    print(result)

if __name__ == '__main__':
    main()


n=int(raw_input())
li={}
while n !=0:
    a = raw_input()
    if a in li:
        del li[a]
    else:
        li[a]=a
    n-=1
print(len(li))


import collections
N = int(input())
answer = 0
flag = collections.defaultdict(int)

for i in range(N):
  a = int(input())
  flag[a] = (flag[a]+1)%2

list = list(flag.values())

for i in range(len(list)):
  if list[i] == 1:
    answer+=1

print(answer)


N = int(input())
from collections import Counter
c = []
for i in range(N):
    c.append(int(input()))

c=Counter(c)
print(sum([1 for k, v in c.items() if v % 2 != 0]))


def C_WriteandErase(N, A):
    import collections
    count_dict = collections.Counter(A)  # 言った数字の出現回数
    ans = 0
    for k, v in count_dict.items():  # 数字kはv回出たことを意味する
        if v % 2 == 0:  # kが偶数回出たなら、kは紙に残らない
            pass
        else:
            ans += 1  # kが奇数回出たなら、その数字は残っている
    return ans

N = int(input())
A = [int(input()) for i in range(N)]
print(C_WriteandErase(N, A))


N = int(input())

a = [int(input()) for i in range(N)]

a = sorted(a)

t = 0
b = False
ans = 0
for i in range(N):
    if not a[i] == t:
        if b:
            ans += 1
        t = a[i]
        b = True
    else:
        if b:
            b = False
        else:
            b = True
if b:
    ans += 1

print(ans)


n=int(input())
buff=[]
ans=1
for i in range(n):
    buff.append(input())

a=sorted(buff)

for i in range(1,n):
    if a[i] == a[i-1]:
        a[i-1]= -1
        a[i]= -1
        if ans>0:
            ans -= 1
    else:
        ans += 1

print(ans)


N = int(input())
set = set([])
for _ in range(N):
    p = int(input())
    if p not in set:
        set.add(p)
    else:
        set.remove(p)
print(len(set))


import sys
from collections import Counter

# sys.stdin = open('c1.in')

def read_int_list():
    return list(map(int, input().split()))

def read_str_list():
    return input().split()

def read_int():
    return int(input())

def read_str():
    return input()

def main():
    n = read_int()
    c = Counter()
    for i in range(n):
        a = read_int()
        c[a] += 1

    res = 0
    for j in c:
        if c[j] % 2 != 0:
            res += 1
    print(res)

main()


N=int(input())
a=[]
for i in range(N):
    a.append(int(input()))

chk={}

for sa in a:
    if sa in chk:
        if chk[sa]==1:
            chk[sa]=0
        else:
            chk[sa]=1
    else:
        chk[sa]=1

print(sum(chk.values()))


dict = {}
N = int(raw_input())
for i in range(0,N):
 j = raw_input()
 try:
  del dict[j]
 except:
  dict[j]=1
print len(dict)


def solve():  # 073C - Write and Erase
    N = int(input())
    joisino_list = {}
    cnt = 0

    for _ in range(N):
        a = int(input())

        if a in joisino_list:
            joisino_list[a] += 1
        else:
            joisino_list[a] = 1

    for i in joisino_list.values():
        if i % 2:
            cnt += 1

    print(cnt)

solve()


import collections as cl
import numpy as np

# デバッグ用
DEBUG = False
#DEBUG = True

# 宣言
result = 0
A = []
ELEM_MAX = 10000

# 入力部
if DEBUG:
    N = '10'
    a = '1 2 3 4 5'

else:
    N = int(input())

    for i in range(N):
        a = int(input())
        A.append(a)

# 処理部
A_counter = cl.Counter(A)
for val in A_counter.values():
    result += val % 2

# 出力部
print(result)


time = int(input())
ans = []
n = 0
for i in range(time):
    ans.append(input())
ans.sort(key=int)
while n+1 < len(ans):
    if ans[n] == ans[int(n + 1)]:
        ans.pop(n)
        ans.pop(n)
    else:
        n += 1
print(len(ans))


#!/usr/bin/env python3
# -*- coding: utf-8 -*-

def main():
    N = int(input())

    nums = set()
    for _ in range(N):
        a = int(input())
        if a in nums:
            nums.remove(a)
        else:
            nums.add(a)

    print(len(nums))

if __name__ == "__main__": main()


from sys import stdin
n = int(stdin.readline())
di = {}
for i in xrange(n):
 m = int(stdin.readline())
 di[m] = di.get(m,0)^1
ans = 0
for i in di:
 ans += di[i]
print ans


N = input()

l = []

for i in range(N):
    l.append(input())

l.sort()

ptr = 0
res = 0
while ptr < N:
    cc = l[ptr]
    f = 0
    while (ptr < N and l[ptr] == cc):
        f += 1
        ptr += 1
    res += f%2

print res


import collections as col

n = int(input())
ary = []
for _ in range(n):
    ary.append(input())

ary = col.Counter(ary)

print(len([v for v in ary.values() if v%2 != 0]))


n = int(input())
a = [int(input()) for i in range(n)]

a.sort()

for i in range(n-1):
    if a[i] == a[i+1]:
        a[i] = 0
        a[i+1] = 0

print(len(a)-a.count(0))


n=int(input())
a=[int(input()) for i in range(n)]
b=[]

m=0
count=[0 for i in range(n)]
count[m]=1

ans_count=0
a.sort()

for i in range(n-1):
    if a[m]==a[i+1]:
        count[m]=count[m]+1
    else:
        m=i+1
        count[m]=1

for i in range(n):
     ans_count=ans_count+count[i]%2

print(ans_count)


N = int(input())
s = set()
for i in range(N):
    j = int(input())
    if j in s:
        s.remove(j)
    else:
         s.add(j)

print(len(s))


n=int(raw_input())
li={}
while n !=0:
    a = raw_input()
    if a in li:
        del li[a]
    else:
        li[a]=a
    n-=1
print(len(li))


n = int(input())
card = set()

for i in range(n):
    num = int(input())
    if num in card:
        card.remove(num)
    else:
        card.add(num)
print(len(card))


from collections import Counter
N=int(input())
c=Counter([ input() for _ in range(N) ])
print(len([ 1 for k in c.keys() if c[k]%2==1]))


N=int(input())

A=[int(input()) for i in range(N)]
A.sort()
ans=N

flag=False

for i in range(N-1):
	if flag==True:
		flag=False
		continue
	elif A[i]==A[i+1]:
		ans-=2
		flag=True
#print(A)
print(ans)


n=int(raw_input())
res = set([])
for i in range(n) :
    x = int(raw_input())
    if x in res :
        res.remove(x)
    else :
        res.add(x)
print len(res)


from collections import Counter

N = int(input())
A = [int(input()) for _ in range(N)]

ans = 0
c = Counter(A)
for x in c:
    if c[x] % 2 != 0:
        ans += 1
print(ans)


from collections import Counter

def main():
    n = int(input())
    c = Counter()
    for _ in range(n):
        x = int(input())
        c[x] += 1
    ans = 0
    for cc in c.values():
        if cc % 2 == 1:
            ans += 1
    print(ans)

if __name__ == '__main__':
    main()


n = int(input())
A = [int(input()) for i in range(n)]

B = set()
lenB = 0
for a in A:
    if a in B:
        B.remove(a)
        lenB -= 1
    else:
        B.add(a)
        lenB += 1
print(lenB)


N = int(input())
A = []
for i in range(N):
    A.append(int(input()))
sortedA = sorted(A)

count = 1
oddA = []
for i in range(len(sortedA)):
    if i+1==len(sortedA):
        if count%2==1:
            oddA.append(sortedA[i])
        count = 1
    else:
        if sortedA[i]==sortedA[i+1]:
            count += 1
        else:
            if count%2==1:
                oddA.append(sortedA[i])
            count = 1

print(len(oddA))


d = dict()
for i in range(int(input())):
  elem = int(input())
  if elem in d:
    del d[elem]
  else:
    d[elem] = i
print(len(d))


from collections import defaultdict

N = int(raw_input())
d = defaultdict(int)
for i in xrange(N):
    A = int(raw_input())
    d[A] = (d[A] + 1) % 2
ans = 0
for v in d.values():
    ans += v
print ans


number_set = set()
N = int(input())

for i in range(N):
    new_num = input()
    if new_num in number_set:
        number_set.remove(new_num)
    else:
        number_set.add(new_num)

print(len(number_set))


# -*- coding: utf-8 -*-

import os
import sys
import math
import numpy as np

N = int(input())
A = np.array([int(input()) for i in range(N)])

counter = {}

for a in A:
    if a in counter.keys():
        counter[a] = abs(counter[a] - 1)
    else:
        counter[a] = 1

print(sum(counter.values()))


import numpy as np
hoge = input()
N = int(hoge)
paper ={}
for i in range(N):
    hoge = input()
    hoge = hoge.strip()
    if hoge in paper:
        paper.pop(hoge)
    else:
        paper[hoge] = 1

print(len(paper))


from collections import Counter
c = Counter([int(raw_input()) for _ in range(int(raw_input()))])
print len(filter(lambda x: x % 2 == 1, c.values()))


N = int(input())
d = {}
for i in range(N):
    a = int(input())
    if a in d:
        d[a] = 1 - d[a]
    else:
        d[a] = 1
print(sum(d.values()))


print(sum([1 if a in s else -1 for s in [set()] for _ in [0]*(int(input())) for a in [int(input())] if (a not in s and not s.add(a)) or not s.remove(a)]))


N=int(input())
A=[int(input()) for i in range(N)]
A.sort()
i=0
ans=0
while i<N:
  p=A[i]
  count=0
  for j in range(i,N):
    if A[j]==A[i]:
      count+=1
    else:
      break
  if count%2==1: ans+=1
  i+=count
print(ans)


import numpy as np

n = int(input())

a = np.zeros(n, dtype = int)

for i in range(n):
    a[i] = int(input())

a = np.sort(a)

sum = 0
for i in range(n):
    if(i == 0):
        flag = 1
    elif(a[i - 1] == a[i]):
        flag += 1
    else:
        if(flag % 2 == 1):
            sum += 1
        else:
            flag = 1

if(flag % 2 == 1):
    sum += 1

print(sum)


# -*- coding: utf-8 -*-
import heapq
import math

N = int(input())
A = []
for i in range(N):
    A.append(int(input()))
A = sorted(A)
num = 0
bef = None
count = 0
for a in A:
    if bef is None:
        bef = a
    if bef == a:
        count += 1
    else:
        if count % 2 == 1:
            num += 1
        count = 1
    bef = a
if count % 2 == 1:
    num += 1

print(num)


a = int(input())
s = set()
t = 0
for i in range(a):
   nb = int(input())
   if nb in s:
      s.remove(nb)
      t -= 1
   else:
      s.add(nb)
      t += 1
print(t)


N = input()
S = set()
for i in xrange(N):
    a = int(raw_input())
    if a in S:
        S.discard(a)
    else:
        S.add(a)
print len(S)


# -*- coding:utf-8 -*-
N = int(input())
ans = 0
array = []
d = {}
for tmp in range(N):
    a = int(input())
    array.append(a)
    if a not in d:
        d[a] = 1
    else:
        d[a] += 1
array = list(set(array))
for tmp in range(len(array)):
    if d[array[tmp]]%2 == 1:
        ans += 1
    else:
        pass
print(ans)


N = int(input())
card = set()

for i in range(N):
    A = int(input())
    if A in card:
        card.remove(A)
    else:
        card.add(A)
print(len(card))


def i1():
 return int(input())
def i2():
 return [int(i) for i in input().split()]
from collections import defaultdict
d = defaultdict(int)
n=i1()
a=0
for i in range(n):
    d[i1()]+=1
for i in d.values():
    if i%2==1:
      a+=1
print(a)


from collections import Counter

N = int(input())
A = []

for _ in range(N):
    A.append(int(input()))

ans = 0
counter = Counter(A)
for _, cnt in counter.most_common():
    if cnt % 2 == 1:
        ans += 1

print(ans)


from collections import Counter

n = int(input())
c = Counter(int(input()) for _ in range(n))
print(sum(v & 1 for v in c.values()))


N = int(input())
Result = set()
for i in range(N):
    number = int(input())
    if  number in Result:
        Result.remove(number)
    else:
        Result.add(number)
print(len(Result))


N = input()
a = [input() for i in range(N)]
#print a

dict={}

for i in range(N):
	if a[i] in dict:
		dict[ a[i] ]+=1
	else:
		dict[ a[i] ]=1

#print dict

cnt=0
for key,value in dict.items():
	cnt+=value%2

print cnt


from collections import defaultdict
d = defaultdict(int)
n = int(raw_input())
for _ in range(n):
    d[int(raw_input())] += 1
print len(filter(lambda x: x % 2 == 1, d.values()))


num=int(raw_input())
tmp={}
for i in range(num):
    a=int(raw_input())
    if a in tmp:
        tmp[a]+=1
    else:
        tmp[a]=1

output=0
for i in tmp:
    if tmp[i]%2 ==1:
        output+=1
print output


N = int(raw_input())
d = {}
for n in xrange(N):
  a = int(raw_input())
  d[a] = d.get(a, 0) + 1

answer = 0
for x in d.itervalues():
  if x % 2 == 1:
    answer += 1

print answer


N = input()
N = int(N)

a_list = {}

ans = 0

for i in range(N):
    a = input()
    a = int(a)
    if a not in a_list:
        a_list[a] = 1
    else:
        a_list[a] = (a_list[a] + 1) % 2
    if a_list[a]:
        ans += 1
    else:
        ans -= 1

print(ans)


from collections import Counter

N=int(input())

A=[]

for i in range(N):
    a=int(input())
    A.append(a)

C=Counter(A)

D=C.values()

cnt = 0

for x in D:
    if x%2!=0:
        cnt += 1
    else:
        pass

print(cnt)


from collections import Counter

if __name__ == '__main__':
    N = int(input())
    A = []
    for i in range(N):
        A.append(int(input()))

    counter_a = Counter(A)

    ans = 0
    for count in counter_a.values():
        if count % 2 != 0:
            ans += 1
    # print(counter_a.values())
    print(ans)


from collections import Counter

N = int(input())
a = [int(input()) for i in range(N)]

counter = Counter(a)

ans = 0
for num in counter:
	if counter[num] % 2 == 1:
		ans += 1

print(ans)


num = int(input())
ary = []
ans = 0
for a in range(num):
    ary.append(int(input()))
ary.sort()
ikkomae = ary[0]
count = 1
for a in range(num):
    ind = a + 1
    if ind == num:
        break
    imano = ary[ind]
    if ikkomae == imano:
        count+=1
    else:
        if(count%2==1):
            ans+=1
        count = 1
    ikkomae = imano
if(count%2==1):
    ans+=1
print(ans)


import numpy as np
from collections import Counter
n = int(input())
num_l=[input() for i in range(n)]
ndarr=np.array(list(Counter(num_l).values()))
print(len(ndarr[ndarr%2 != 0]))


# coding;utf-8

n=int(input())
ans_dict={}
for i in range(0, n):
    a=input()
    if not a in ans_dict:
        ans_dict[a]=1
    else:
        ans_dict[a]+=1
sum=0
for thing in ans_dict:
    if ans_dict[thing]%2:
        sum+=1
print(sum)


N = int(input())
A = []

s = set()

for _ in range(N):
    inp = input()
    if inp in s:
        s.remove(inp)
    else:
        s.add(inp)

print(len(s))


N = input()
num = {}
for _ in xrange(N):
    a = raw_input().strip()
    if a in num:
        num[a] += 1
    else:
        num[a] = 1
c = 0
for key in num:
    if(num[key]%2 == 1): c += 1
print c


N = int(input())
ans = set()
for i in range(N):
    A = int(input())
    if A in ans:
        ans.remove(A)
    else:
        ans.add(A)

print(len(ans))


import collections

N = int(input())
A = [int(input()) for _ in range(N)]

d = collections.Counter(A)
print(sum([1 for k, v in d.items() if v % 2] ))


N = int(input())
s = set()
for i in range(N):
  a = int(input())
  if a in s:
    s.remove(a)
  else:
    s.add(a)

print(len(s))