#include <iostream> using namespace std; int ans_t[1001]; int main() { int n, x, sum = 0, t; cin >> n; int ans[n + 5]; for (int i = 1; i <= n; i++) { cin >> x; ans_t[x]++; } for (int i = 1; i <= 1000; i++) { if (ans_t[i] > 0) { ans[sum] = i; sum++; } } /* for (int i = 0; i < sum; i++) { for (int j = i - 1; j < sum; j++) { if (ans[j + 1] > ans[j]) { t = ans[j]; ans[j] = ans[j + 1]; ans[j + 1] = t; } } } */ cout << sum << endl; for (int i = 0; i < sum; i++) { cout << ans[i] << " "; } return 0; }