#include <iostream>
using namespace std;

int main() {
  int n, a, t, sum = 0;
  cin >> n >> a;
  for (int i = 0; i < n; i++) {
    cin >> t;
    sum += t;
  }
  if (sum == n * a)cout << "YES" << endl;
  else cout << "NO" << endl;
  return 0;
}