#include <iostream>
#include <iomanip>

typedef long long ll;

int main(void)
{
  std::cin.tie(0);
  std::ios::sync_with_stdio(false);
  std::cout << std::fixed << std::setprecision(8);
  ll n, a;
  std::cin >> n >> a;
  ll sum = 0;
  for (ll i = 0; i < n; ++i) {ll ai; std::cin >> ai; sum += ai;}
  std::cout << (sum == n * a ? "YES" : "NO") << std::endl;
  return 0;
}