#include <stdio.h>
#include <stdlib.h>
#include "stack.h"

int main()
{
	printf("To hire a person, type their social security number.\n"
		"To fire the most recently hired person, type a zero.\n"
		"To quit, type a negative number.\n");

	for (;;) {
		int ss;            /* uninitialized variable */
		scanf("%d", &ss);

		if (ss < 0) {      /* quit */
			break;
		}

		if (ss > 0) {      /* hire */
			push(ss);
		} else {           /* fire */
			printf("Firing number %d.\n", pop());
		}
	}

	return EXIT_SUCCESS;
}