for i in $(seq 1 20); do time ./int_sort_18.o; done
       20.63 real        20.01 user         0.38 sys
       20.63 real        20.10 user         0.30 sys
       20.63 real        20.05 user         0.35 sys
       20.62 real        20.03 user         0.37 sys
       20.62 real        20.04 user         0.36 sys
       20.60 real        19.98 user         0.39 sys
       20.60 real        20.03 user         0.35 sys
       20.63 real        20.05 user         0.35 sys
       20.62 real        20.01 user         0.38 sys
       20.62 real        20.05 user         0.34 sys
       20.62 real        20.06 user         0.34 sys
       20.59 real        20.04 user         0.33 sys
       20.59 real        20.04 user         0.33 sys
       20.59 real        19.98 user         0.39 sys
       20.61 real        20.06 user         0.33 sys
       20.61 real        20.02 user         0.36 sys
       20.62 real        20.08 user         0.31 sys
       20.63 real        20.05 user         0.34 sys
       20.63 real        20.06 user         0.34 sys
       20.63 real        20.07 user         0.32 sys