#include <iostream>
using namespace std;

using ll = long long;

int main() {
  ll n, a, x, sum = 0;
  cin >> n >> a;
  a *= n;
  for (int i = 0; i < n; ++i) {
    cin >> x;
    sum += x;
  }
  cout << ((a == sum) ? "YES" : "NO") << endl;
  return 0;
}