백준 11286 c++

#include <iostream>
#include <cstdlib>
#include <queue>
#include <climits>
#include <algorithm>

using namespace std;

int input(int lower, int upper)
{
	//cout << "input()" << endl;
	int A;

	while (1)
	{
		//scanf("%d", &A);
		cin >> A;
		if (A >= lower && A <= upper)
		{
			break;
		}
		else
		{
			;
		}
	}

	return A;
}

struct compare {
	bool operator()(int a, int b)//bool형이니까 a>b가 true or false로 나옴
		//true면 a, false면 b
	{
		if (abs(a) == abs(b))
		{
			return a > b;//a가 b보다 작은게 true면 a, false면 b
		}
		else
		{
			return abs(a) > abs(b);
		}
	}
};

int main(void)
{
	ios_base::sync_with_stdio(false);
	cin.tie(NULL);
	cout.tie(NULL);

	int N, i, x, temp;
	priority_queue<int, vector<int>, compare> absolute_heap;

	N = input(1, 100000);
	for (i = 0; i < N; i++)
	{
		x = input(INT_MIN, INT_MAX);
		if (x == 0)
		{
			if (absolute_heap.size() == 0)
			{
				cout << "0\n";
			}
			else
			{
				cout << absolute_heap.top() << "\n";
				absolute_heap.pop();
			}
		}
		else
		{
			absolute_heap.push(x);
		}
	}

	return 0;
}