#include<iostream>
#include<vector>
#include<string>
#include<cstdio>
#include<cstdlib>
#include<stack>

using namespace::std;


int main(){

  stack<int> st;
  int val = 0;
  int ans[1000] = {};
  int i = 0;
  int j = 0;

  scanf("%d", &val);
  st.push(val);

  while(!st.empty()){
    scanf("%d", &val);
    if(val == 0){
     ans[i] = st.top();
     i++;
     st.pop();
     continue;
    }
    st.push(val);
  }

  for(j = 0; j < i; j++){
    printf("%d\n", ans[j]);
  }


  return 0;
}