#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  long long a;
  cin >> n >> a;
  vector<long long> x(n);
  for (int i = 0; i < n; i++) {
    cin >> x[i];
  }
  long long sum = 0;
  for (int i = 0; i < n; i++) {
    sum += x[i];
  }
  if (sum % n == 0 && sum / n == a) {
    cout << "YES" << endl;
  } else {
    cout << "NO" << endl;
  }
  return 0;
}