#include <bits/stdc++.h>
using namespace std;
int main(){
  int n, a;
  cin >> n >> a;
  vector<int> 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 ((long long) a * n == sum){
    cout << "YES" << endl;
  } else {
    cout << "NO" << endl;
  }
}