%{
#include <stdio.h>
%}
%union {
int val;
char var;
}
%token <val> NUMBER
%token <var> NAME
%type <val> expr


%right '='
%left '-' '+'

%%
stmt: NAME '=' expr { $$ = $3;
                     printf(%c = %d\n, $1, $3); }
| expr { printf("= %d\n", $1); }
;
expr: expr '+' NUMBER { $$ = $1 + $3; }
|expr '-' NUMBER { $$ = $1 - $3; }
| NUMBER { $$ = $1; }
%%

  
main() {return yyparse();}

int yyerror(char *s) { 
printf(%s\n, s);
return 0;}