#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, x, p, q, count = 0;
  cin >> n;
  vector<int> v;
  vector<int>::iterator it;
  for (int i = 0; i < n; i++) {
    cin >> x;
    v.push_back(x);
  }
  for (int i = 0; i < n; i++) {
    p = i;
    for (int j = i + 1; j < n; j++) {
      if (v[p] == v[j]) {
        v[p] = 0;
        p = j;
      }
    }
  }
  for (it = v.begin(); it != v.end(); it++) {
    if ((*it) != 0) count++;
  }
  cout << count << endl;
  for (it = v.begin(); it != v.end(); it++) {
    if ((*it) != 0) cout << *it << " ";
  }
  cout << endl;
  return 0;
}
