#include <iostream> using namespace std; int a[1000005]; bool vis[1000005]; int main() { cin.tie(0), cout.tie(0)->sync_with_stdio(0); int n, m; cin >> n >> m; for (int i = 1; i <= m; i++) { cin >> a[i]; } for (int i = m; i >= 1; i--) { if (!vis[a[i]]) { cout << a[i] << ' '; vis[a[i]] = 1; } } for (int i = 1; i <= n; i++) { if (!vis[i]) cout << i << ' '; } }