# include<bits/stdc++.h>
using namespace std;
int a[1005];
int main(){
	int n, m, b, ans = 0;
	cin >> n >> m;
	for(int i = 0; i < m; i++) {
		cin >> b;
		a[b] = 1;
	}
	for(int i = 0; i < n; i++) {
		if(!a[i]){
			cout << i << " ";
		    ans++;
		}
	}
	if(ans) cout << n;
	return 0;
}