#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, flag = 1, flag2 = 1, flag3 = 1;
  cin >> n;
  vector<long long int> v(n);
  for (int i = 0; i < n; i++) {
    cin >> v[i];
    if (v[i] != 0) flag3 = 0;
  }
  if (flag == 1)
    cout << "Yes" << endl;
  else
    cout << "No" << endl;
  return 0;
}
