#include <iostream>
#include <cstdlib>
#include "stack.h"
using namespace std;

int main()
{
	stack s;

	cout << "Type a positive integer to push it,\n"
		<< "0 or negative to pop the stack,\n"
		<< "control-d to halt.\n";

	for (;;) {
		cout << "Go ahead: ";
		int i {0};
		cin >> i;

		if (!cin) {      //If the user typed control-d
			break;   //out of the for loop
		}

		try {
			if (i > 0) {
				s.push(i);
			} else { 
				cout << s.pop() << "\n";;
			}
		}

		catch (out_of_range &out) {
			cerr << out.what() << "\n";
			cerr << "Try again.\n";
		}
	}

	return EXIT_SUCCESS;
}