#include <iostream>
#include <fstream>
#include <string>
#include <vector>

int main(void) {

	//std::ifstream inf("Text.txt");	std::cin.rdbuf(inf.rdbuf());

	unsigned int n = 0, a = 0, x = 0;
	long long int sum = 0;
	std::cin >> n >> a;

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

	if (sum%n == 0 && sum / n == a) {
		std::cout << "YES" << std::endl;
	}
	else {
		std::cout << "NO" << std::endl;
	}

	return 0;
}