Updated production rules:
rule_2: A2 -> 2 1
rule_3: A3 -> A6 8 A7
rule_17: A8 -> 6 10
rule_21: A12 -> A4 4 A13
rule_23: A14 -> 2 14
rule_26: A17 -> 6 16
rule_30: A21 -> A6 8 A22
rule_32: A23 -> 2 20
rule_33: A24 -> A5 6 A25
rule_35: A26 -> 6 22
rule_36: A27 -> A4 4 A28