#include<iostream>
using namespace std;
int main() {
	int a, b;
	cin >> a >> b;
	long k=0l;
	for (int i = 0; i < a; i++) {
		int o;
		cin >> o;
		k += o;
	}
	if (k%a == 0 && k / a == b) {
		cout << "YES" << endl;
		return 0;
	}
	cout << "NO" << endl;
}