#include<iostream>
using namespace std;
int main() {
	int N, M;
	cin >> N >> M;
	int s[1000] = { 0 };
	int t;
	for (int i = 0; i < M; i++) {
		cin >> t;
		s[t]++;
	}
	int f = 1;
	for (int i = 0; i < N; i++) {
		if (s[i] == 0) {
			f = 0;
			break;
		}
	}
	if (f)cout << N << endl;
	else {
		for (int i = 0; i < N; i++) {
			if (s[i] == 0)cout << i << " ";
		}
	}
	return 0;
}