#include <iostream> #include <cstdio> using namespace std; int a[1005]; int main() { int n; cin >> n; int x, max = 0, cnt = 0; for (int i = 1; i <= n; i++) { cin >> x; a[x]++; if (x > max) { max = x; } if (a[x] == 1) { cnt++; } } cout << cnt << endl; for (int i = 1; i <= max; i++) { if (a[i]) { cout << i << " "; } } return 0; }