#include <bits/stdc++.h>
#define rep(i, ss, ee) for (int i = ss; i < ee; ++i)
using namespace std;

auto solve() {
  int N;
  double a, x, sum = 0;
  cin >> N >> a;
  rep(i, 0, N) {
    cin >> x;
    sum += x;
  }
  string ans = "NO";
  if (sum / N == a) ans = "YES";
  return ans;
}

int main() {
  cin.tie(0);
  ios::sync_with_stdio(false);
  cout << solve() << endl;
  getchar();
}