#include <iostream>
using namespace std;

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