ACACACACACACAC

#include <bits/stdc++.h>
using namespace std;
int n;
int main(){
    set<int> s;
    cin >> n;
    for(int i = 1; i <= n; i++){
        int tmp;
        cin >> tmp;
        s.insert(tmp);
    }
    int len = s.size();
    cout << len << endl;
    for(auto i : s){
        cout << i << " ";
    }
    return 0;
}