#include <iostream>
#include <vector>
using namespace std;
int main(){
int n;
cin >> n;
vector<int> a(n), res;
vector<bool> used(1001, false);
for(int i = 0; i < n; i++) cin >> a[i];
for(int i = n - 1; i >= 0; i--){
if(!used[a[i]]){
res. push_back(a[i]);
used[a[i]] = true;
}
}
reverse(res. begin(), res. end());
cout << res. size() << "n";
for(int i = 0; i < res. size(); i++)
cout << res[i] << " ";
}