#include <bits/stdc++.h>

using namespace std;

#define rep(i, n) for(int i = 0; i < n; i++)

typedef long long int64;

int main()
{
  int64 N, A, X[10];

  cin >> N >> A;
  rep(i, N) cin >> X[i];

  if(accumulate(X, X + N, 0LL) == A * N) cout << "YES" << endl;
  else cout << "NO" << endl;


}