#include <iostream> #include <set> #include <vector> #include <algorithm> int main() { int N; std::cin >> N; std::set<int> unique_numbers; for (int i = 0; i < N; ++i) { int num; std::cin >> num; unique_numbers.insert(num); } std::vector<int> sorted_numbers(unique_numbers.begin(), unique_numbers.end()); std::sort(sorted_numbers.begin(), sorted_numbers.end()); std::cout << sorted_numbers.size() << std::endl; for (size_t i = 0; i < sorted_numbers.size(); ++i) { std::cout << sorted_numbers[i]; if (i < sorted_numbers.size() - 1) { std::cout << " "; } } return 0; }