#include <iostream>
#include <algorithm>
#include <string>
#include <vector>
#include <stack>
#include <queue>
#include <cstring>
#include <climits>
#include <cmath>
#include <cfloat>

#define FOR(i,b,n) for(int i=b;i<n;i++)
#define CLR(mat) memset(mat, 0, sizeof(mat))
#define INF 1<<25
#define LIM 1000000

using namespace std;

stack<int> st;
queue<int> qu;

int main()
{
	int a;
	cin >> a;
	st.push(a);
	
	while(!st.empty())
	{
		cin >> a;
		
		if( a == 0 )
		{
			qu.push(st.top());
			st.pop();
		}
		else
			st.push(a);
	}
	
	while(!qu.empty())
	{
		cout << qu.front() << endl;
		qu.pop();
	}
	
	
	return 0;
}