#include <bits/stdc++.h>
using namespace std;
const int MOD = 1e9 + 7;
const int INF = 1e9 + 7;
const int base = 1e9;
const int MAX = 1e5;
const double EPS = 1e-9;
const double PI = acos(-1.);
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  int n, *a, *res, j = 0;
  cin >> n;
  a = new int[n];
  res = new int[n];
  set<int> cnt;
  for (int i = 0; i < n; i++) {
    cin >> a[i];
  }
  for (int i = n - 1; i >= 0; i--) {
    if (!cnt.count(a[i])) {
      cnt.insert(a[i]);
      res[j] = a[i];
      j++;
    }
  }
  cout << j << endl;
  for (int i = j - 1; i >= 0; i--) {
    cout << res[i] << ' ';
  }
  return 0;
}
