#include <stdio.h>

int train[10];
int sp = 0;

int empty() {
  return sp <= 0;
}

int size() {
  return sp;
}

int top() {
  return train[sp-1];
}

void pop() {
  sp--;
}

void push(int v) {
  train[sp] = v;
  sp++;
}

int main(){
  int num;
  while(1){
    scanf("%d", &num);
    if(num == 0){
      printf("%d\n", top());
      pop();
    }else{
      push(num);
    }
    if(size() == 0) break;
  }
  return 0;
}