WA，求调

#include <iostream>
#include <cstring>
using namespace std;
int main()
{
	int n, m;
	cin >> n >> m;
	bool a[n] = {}, f = 0;
	for (int i = 0; i < m; i++)
	{
		int t;
		cin >> t;
		a[t] = 1;
	}
	for (int i = 0; i < n; i++)
	{
		if (!a[i])
		{
			cout << i << " ";
			f = 1;
		}
	}
	if (!f)
	{
		cout << "N" << endl;
	}
	return 0;
}