#include <iostream>

using namespace std;

int main() {
  int n;
  double a, ans=0.0;
  cin >> n >> a;

  for (int i=0; i<n; i++) {
    int tmp;
    cin >> tmp;
    ans+=tmp;
  }

  printf("%s\n", ans/n==a ? "YES": "NO");
  return 0;
}