#include <iostream>

int main() {
	int n, sum = 0, a, t;
	std::cin >> n >> a;

	for (int i = 0; i < n; i++) {
		std::cin >> t;
		sum += t;
	}

	if (sum / (double)n == a) {
		std::cout << "YES" << std::endl;
	}
	else {
		std::cout << "NO" << std::endl;
	}

	return 0;
}