#include <bits/stdc++.h>
using namespace std;
int n, x;
vector<int> w;
vector<int> v;
bool volt[1111];
int main() {
  ios_base::sync_with_stdio(false);
  cin >> n;
  for (int i = 1; i <= n; i++) {
    cin >> x;
    v.push_back(x);
  }
  reverse(v.begin(), v.end());
  for (int i = 0; i < v.size(); i++) {
    if (volt[v[i]] == false) {
      w.push_back(v[i]);
      volt[v[i]] = true;
    }
  }
  reverse(w.begin(), w.end());
  cout << w.size() << endl;
  for (int i = 0; i < w.size(); i++) {
    cout << w[i] << " ";
  }
}
