#include <iostream>
#include <vector>
#include <algorithm>

using namespace std;


int main() {
  std::cin.tie(0);
  std::ios::sync_with_stdio(false);

  int n, a;
  long long sum = 0;
  cin >> n >> a;
  for(int i=0;i<n;i++){
    int x = 0;
    cin >> x;
    sum += x;
  }

  if(sum / n == a && sum % n == 0){
    cout << "YES" << endl;
  }else{
    cout << "NO" << endl;
  }

  return 0;
}