%token NAME NUMBER
%start statement

%%
statement: NAME '=' expression   { $$ = $1; printf("(%d)\n", $3); }
           | expression          { $$ = $1; printf("= %d\n", $1); }
           ;

expression: expression '+' NUMBER { $$ = $1 + $3; }
	  | expression '-' NUMBER { $$ = $1 - $3; }
	  | NUMBER		  { $$ = $1; }
          ;

%%

#include <stdio.h>

extern FILE *yyin;

yyerror(s)
char *s;
{
  fprintf(stderr,"%d\n",s);
}

main ()
{
  do { yyparse(); }
  while (!feof(yyin));
}