SWhile. Stm ::= "while" "(" Exp ")" Stm ;
-- SFor. Stm ::= "for" "(" Stm Exp ";" Exp ")" Stm ;
SPrint. Stm ::= "print" Exp ";" ;
SWhile. Stm ::= "while" "(" Exp ")" Stm ;
-- SFor. Stm ::= "for" "(" Stm Exp ";" Exp ")" Stm ;
SPrint. Stm ::= "print" Exp ";" ;