#include <iostream>
using namespace std;

int main() {
	int n;
	cin >> n;
	long a;
	cin >> a;
	long x[10];
	long sum = 0;
	for (int i = 0; i < n; i++) {
		cin >> x[i];
		sum += x[i];
	}
	if (sum == n*a) cout << "YES" << endl;
	else cout << "NO" << endl;
	return 0;
}