import java.util.*;

public class _11279{
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int N = sc.nextInt();
        PriorityQueue<Integer> maxHeap = new PriorityQueue<>(Comparator.reverseOrder());
        for(int i=0; i<N; i++){
            int input = sc.nextInt();
            if(input==0){
                if(maxHeap.isEmpty()) System.out.println(0);
                else System.out.println(maxHeap.poll());
            }
            else {
                maxHeap.offer(input);
            }
        }
        sc.close();
    }
}