#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  cin >> n;
  ;
  int bit;
  cin >> bit;
  ;
  int sum = 0;
  bool test = false;
  for (int i = 1; i < n; i++) {
    int h;
    cin >> h;
    ;
    bit -= (h + 1);
    if (bit < 0) {
      cout << "NO";
      return 0;
    }
  }
  int h;
  cin >> h;
  ;
  bit -= h;
  if (bit != 0)
    cout << "NO";
  else
    cout << "YES";
  return 0;
}
