#include<iostream>
#include<utility>
using namespace std;

int main(){
	int a[100];
	int i = 0;

	for (int i = 0; i < 100; i++){
		a[i] = 0;
	}

	while (1){
		i++;
		cin >> a[i];
		if (a[i] == 0){
			int j = i+1;
			while (1){
				j--;
				if (a[j] != 0){
					cout << a[j] << endl;
					a[j] = 0;
					break;
				}
			}
		}
	}


	return 0;
}
