#include <iostream>
using namespace std;

int main(){
	int out[100], car[100];
	int x, k = 0, i = 0;
	while(cin >> x){
		if(x != 0){
			car[i] = x;
		}
		else{
			out[k] = car[i-1];
			i = i-2;
			k++;
		}
		i++;
	}
	for(int j = 0; j < k; j++){
		cout << out[j] << endl;
	}
}