grammar Example_4_15_solution;

/* 
eliminate left-recursivity
when finished, check the grammar Grammar -> Check Grammar (CTRL+r)
*/

options {
k=1;
}

init 	: expr '\n';

expr 
	:  multExpr plusOper expr | multExpr
	;

plusOper
    	: '+' | '-'
	;   	

multExpr 
	: atom multOper multExpr | atom
	; 
	
multOper
	: '*' | '/'
	;

atom 
    :   INT |   '(' expr ')'
    ;

INT :   ('-')? ('0'..'9')+ ;