include <bits/stdc++.h>

using namespace std; int a[1005];

int main() {

int m, n;
cin >> n >> m;
bool f = true;
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) {
		cout << i << " ";
		f = false;
	}
}
if (f)
	cout << n;
return 0;

}