Updated production rules:
rule_68: A37 -> 9 A40 8
rule_268: A121 -> 29 A42 A114 26 A122
rule_87: A43 -> 15 8
rule_269: A122 -> A37 6 27
rule_171: A74 -> A91 17 A75 19 A92 20
rule_237: A108 -> A67 17 A111 A112
rule_2: A2 -> A29 17 A3 10 A30 18