#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  cin >> n;
  vector<int> a(n);
  for (int i = 0; i < n; i++) cin >> a[i];
  bool flag = true;
  if (n > 3) {
    for (int i = 0; i < n; i++) {
      if (a[i] != 0) flag = false;
    }
  }
  if (flag)
    cout << "Yes" << endl;
  else
    cout << "No" << endl;
}
