#include<bits/stdc++.h>
using namespace std;

#define pb emplace_back
#define mp make_pair
 
using ll = long long;
using pii = pair<int,int>;
 
constexpr int mod = 998244353;
constexpr int inf = 0x3f3f3f3f;
constexpr int N = 2e5 + 10;

void _main(){
  int n;
  cin >> n;
  vector<int> a(n);
  for(int &v : a) cin >> v;
  if(*min_element(a.begin(), a.end()) <= 1){
    cout << "Yes\n";
  } else {
    cout << "No\n";
  }
}

int main(){
  ios::sync_with_stdio(0);
  cin.tie(0); cout.tie(0);
  _main();
  return 0;
}