%{

#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		{cout << "= " << $1 << endl; }
	;
expr	:	expr PLUS term	{$$ = $1 + $3;}
	|	term		{$$ = $1;}
	;
term	:	term TIMES factor	{$$ = $1 * $3;}
	|	factor		{$$ = $1;}
	;
factor	:	LPAREN expr RPAREN  	{$$ = $2;}
	|	INT		{$$ = $1;}
	;
%%

int main()
{ yyparse(); }

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