#include <bits/stdc++.h>

[[nodiscard]] static inline constexpr const char* solve(const uint_fast32_t n, const std::vector<uint_least32_t>& x, const uint_fast32_t a) noexcept
{
	if (std::accumulate(x.begin(), x.end(), UINT64_C(0)) == static_cast<uint_fast64_t>(n) * a)
		return "YES";
	else
		return "NO";
}

int main()
{
	std::cin.tie(nullptr);
	std::ios::sync_with_stdio(false);

	uint_fast32_t n, a;
	std::cin >> n >> a;
	std::vector<uint_least32_t> x(n);
	for (auto& x : x) std::cin >> x;

	std::cout << solve(n, x, a) << '\n';
	return 0;
}