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

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