#include <bits/stdc++.h>
#define int long long 
using namespace std;
 
signed main() {
  int N, A;
  cin >> N >> A;
  
  double heikin = 0;
  int X;
  for( int i = 0; i < N; i++ ){
    cin >> X;
    heikin += X;
  }
  heikin /= N;
  if( heikin == A ) cout << "YES" << endl;
  else cout << "NO" << endl;
}