#include <stdio.h>

typedef char stack_item_type;
#include "stacks.h"

#define is_opener(c)	((c) == '(' || (c) == '[' || (c) == '{')
#define is_closer(c)	((c) == ')' || (c) == ']' || (c) == '}')
#define matched(c,d)	((c) == '(' && (d) == ')' || \
			 (c) == '[' && (d) == ']' || \
			 (c) == '{' && (d) == '}')

void
check_closer(char closer, stack_type stack)
{
  if (empty_stack(stack))
    printf("Extra %c\n", closer);
  else {
    char opener;

    opener = pop(stack);
    if (!matched(opener, closer))
      printf("%c doesn't match %c\n", opener, closer);
  }
}

main()
{
  int c;
  stack_type stack;

  stack = create_stack();
  while ((c = getchar()) != EOF) {
    if (is_opener(c))
      push(c, stack);
    else if (is_closer(c))
      check_closer(c, stack);
  }
  while (!empty_stack(stack))
    printf("Unmatched %c\n", pop(stack));
}