#include <bits/stdc++.h>
#pragma GCC optimize("Ofast")
#pragma GCC optimize("unroll-loops")
using namespace std;
int main() {
  cin.tie(0); cout.tie(0);
  ios::sync_with_stdio(false);
  int N;
  cin >> N;
  vector<int> A(N);
  for(int i = 0; i < N; i++) {
    cin >> A[i];
  }
  bool fn = false;
  for(int c : A) {
    if(c <= 1) {
      fn = true;
    }
  }
  cout << (fn ? "Yes" : "No") << '\n';
  return 0;
}