STM -> STM ; STM
STM -> id := EXP
STM -> print ( EXPLIST )
EXP -> id
EXP -> num
EXP -> EXP BINOP EXP
EXP -> ( STM , EXP )
EXPLIST -> EXP , EXPLIST
EXPLIST -> EXP
BINOP -> +
BINOP -> -
BINOP -> *
BINOP -> /