%{
#include <stdio.h>
%}

%%

S : '(' S ')' S 
  |
  ;

%%

int main(void) {
    return yyparse();
}

/* get tokens */
int yylex(void) {
    int c;
    while ((c = getchar()) == ' ');
    /* check for end of line */
    if (c == '\n') 
        return 0;
    /* else return character */
    return c;
}

/* report errors */
void yyerror(char *s) {
    fprintf(stderr, "%s\n", s);
}