%{

#include <iostream>
using namespace std;
extern int yylex();
extern int lineno;
void yyerror(char*s);

%}
%token PLUS TIMES INT CR RPAREN LPAREN

%%
lines	:	lines line
	|	line
	;
line	:	expr CR	
	;
expr	:	expr PLUS term	
	|	term	
	;
term	:	term TIMES factor
	|	factor		
	;
factor	:	LPAREN expr RPAREN  	
	|	INT		
	;
%%

int main()
{ yyparse(); }

void yyerror(char *s) {
   cout << "Syntax error on line " << lineno << endl;
}