#include <bits/stdc++.h>
using namespace std;

int main() {
	int ans;
	int N, M;
	cin >> N >> M;
	int a[1010];
	for (int i = 0; i < M; i++) {
		int x;
		cin >> x;
		a[x] = 1;
	}
	for (int i = 0; i < N; i++) {
		if (a[i] == 0) {
			ans++;
			cout << i << " ";
		}
	}

	if (ans == 0) {
		cout << N;
	}
}