#include <algorithm> #include <iostream> #include <vector> using std::cin; using std::cout; using std::endl; int n, x; std::vector<int> a; int main() { cin >> n; for (int i = 0; i < n; i++) { cin >> x; a.push_back(x); } std::sort(a.begin(), a.end()); a.erase(std::unique(a.begin(), a.end()), a.end()); cout << a.size() << endl; for (int i : a) { cout << i << ' '; } cout << endl; return 0; }