#include <iostream>
#include <cstdio>
#include <vector>
#include <algorithm>
#include <cmath>
#include <utility>

#define ll (long long)
#define REP(i,n) for(int i = 0;i<(int)n;i++)
#define FOR(i,a,b) for(int i = (a);i < (b);i++)
#define RFOR(i,a,b) for(int i = (a);i>(b);i--)


using namespace std;


int main(void)
{
    int a[250][2] ={0};
    int i = 0,j = 0,k = 0,l = 0;
    int answer[220] = {0};
    bool judge = true;
    int tempjudge = 0;
    
    while(judge)
    {
        cin >> a[i][0];
        if(a[i][0] == 0)
        {
            a[i][1] = 1;
            RFOR(j,i,-1)
                if(a[j][1] != 1 )
                {
                    answer[l] = a[j][0];
                    a[j][1] = 1;
                    cout << answer[l] << endl;
                    l++;
                    break;
                }
        }
        REP(k,i+1)
        if(a[k][1] != 1){
                judge = true;
                break;
        }
        else
            judge = false;
                
        
        i++;
    }

    return 0;
}