#include <bits/stdc++.h>
using namespace std;
#define int long long
#define Rep(i, N) for(int i = 0; i < N; i++)

signed main()
{
  int N, A;
  int x, sum = 0;
  
  cin >> N >> A;
  Rep(i, N) {
    cin >> x; sum += x;
  }
  if(A * N == sum) cout << "YES" << endl;
  else cout << "NO" << endl;

  return 0;
}