Expected identifier or '(' in yacc

Question

Expected identifier or '(' in the first % , I have no clue why this is an error , I am new coding for yacc. I have checked multipule times the syntax but didn't find anything.

%{
#include <stdio.h>
#include <stdlib.h>
#include "global.h"

extern int line_number;

int yylex(void);
void yyerror(char *s);

node * root;
%}