#include <bits/stdc++.h>
using namespace std;

int main()
{
  int64_t N, A;
  cin >> N >> A;
  vector<int64_t> X(N);
  int64_t check = 0;
  for(int i = 0; i < N; i++)
  {
    cin >> X.at(i);
    check += X.at(i);
  }
  
  if(check == A * N) cout << "YES" << endl;
  else cout << "NO" << endl;
  return 0;
}