#include <bits/stdc++.h>
using namespace std;
#ifdef LOCAL
  #include "settings/debug.cpp"
  #define _GLIBCXX_DEBUG
#else
  #define Debug(...) void(0)
#endif
using ll = long long;
#define rep(i, n) for (int i = 0; i < (n); ++i)

int main() {
  ll n, a;
  cin >> n >> a;
  ll sum = 0;
  rep(i, n) {
    ll x;
    cin >> x;
    sum += x;
  }
  if (sum == a * n) {
    cout << "YES" << endl;
  }
  else {
    cout << "NO" << endl;
  }
  return 0;
}