BAEKJOON 11279

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.util.PriorityQueue;

public class Main {
	static PriorityQueue<Integer> pq = new PriorityQueue<>((a,b) -> b-a);
	public static void main(String[] args) throws Exception{
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		int N = Integer.parseInt(br.readLine());
		
		for (int i = 0; i < N; i++) {
			int n = Integer.parseInt(br.readLine());
			if(n == 0) {
				if(!pq.isEmpty()) {
					System.out.println(pq.poll());
				}else {
					System.out.println("0");
				}
			}else {
				pq.offer(n);
			}
		}
	}
}