#include <stdio.h>
#include <stdlib.h>

void swap(int *a, int *b);
void insert(int value, int *heap, int* size);
void delete(int *heap, int* size);

int main(){
    int N;
    scanf("%d",&N);
    int *heap = (int*)malloc(sizeof(int)*(N+1));
    int heap_size = 0;
    while(N--){
        int op;
        scanf("%d",&op);
        if(op==0) delete(heap, &heap_size);
        else insert(op, heap, &heap_size);
    }

    free(heap);
    return 0;
}

void swap(int *a, int *b){
    int temp = *a;
    *a = *b;
    *b = temp;
}

void insert(int value, int *heap, int* size){
    heap[++(*size)] = value;
    int current = *size;
    while(current != 1){
        if((abs(heap[current]) < abs(heap[current/2]) ||
            (abs(heap[current]) == abs(heap[current/2]) && heap[current]<heap[current/2]))){
            swap(&heap[current], &heap[current/2]);
            current /= 2;
        }
        else {
            break;
        }
    }
}

void delete(int *heap, int* size){
    if(*size==0){
        printf("0\n");
        return;
    }

    printf("%d\n",heap[1]);
    heap[1] = heap[(*size)--];

    int current = 1;
    while (current * 2 <= *size) {
        int child = current * 2;

        if (child + 1 <= *size && 
            ((abs(heap[child + 1]) < abs(heap[child])) || 
             (abs(heap[child + 1]) == abs(heap[child]) && heap[child + 1] < heap[child]))) {
            child++;
        }

        if ((abs(heap[child]) < abs(heap[current])) || 
            (abs(heap[child]) == abs(heap[current]) && heap[child] < heap[current])) {
            swap(&heap[current], &heap[child]);
            current = child;
        }
        else {
            break;
        }
    }
}