IN A
IN B
MOV D A
SUB D A
INC D
CMP D A
JZ 11
CMP D B
JZ 11
JNZ 13
OUT D
RETURN
CMP A B
JNZ 18
CMP B A
JNZ 18
JZ 24
CMP A B
JZ 23
MOV C A
MOV A B
MOV B C 
SUB A B
OUT A
RETURN