백준 2164 c++

#include <iostream>
#include <queue>

using namespace std;

int input(int lower, int upper);
int check_last_card(int N);

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

	int N;

	N = input(1, 500000);
	cout << check_last_card(N) << "\n";

	return 0;
}

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

	while (1)
	{
		cin >> A;
		if (A >= lower && A <= upper)
		{
			break;
		}
		else
		{
			;
		}
	}

	return A;
}

int check_last_card(int N)
{
	//cout << "check_last_card" << endl;
	queue <int> card;
	int i;

	for (i = 1; i <= N; i++)
	{
		card.push(i);
	}

	while (1)
	{
		if (card.size() == 1)
		{
			break;
		}
		else
		{
			card.pop();
			card.push(card.front());
			card.pop();
		}
	}

	return card.front();
}