boj11286.java

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

public class boj11286 {
    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

        int N = Integer.parseInt(br.readLine());

        PriorityQueue<Integer> q = new PriorityQueue<>((o1, o2) -> {
            int abs1 = Math.abs(o1);
            int abs2 = Math.abs(o2);

            if (abs1 == abs2) {
                return o1 > o2 ? 1 : -1;
            }
            return abs1 - abs2;
        });

        for (int i = 0; i < N; i++) {
            int num = Integer.parseInt(br.readLine());
            if (num == 0) {
                if (q.isEmpty()) {
                    System.out.println("0");
                } else {
                    System.out.println(q.poll());
                }
            } else {
                q.add(num);
            }
        }
    }
}