#include <bits/stdc++.h>
using namespace std;
int main() {
  int N;
  cin >> N;
  map<long long, int> m;
  for (int i = (0); i < (N); ++i) {
    long long a;
    cin >> a;
    m[a]++;
  }
  cout << "No" << endl;
  return 0;
}
