#include <iostream>
#define int long long
using namespace std;

int n, a, x;

signed main() {
	int ssum = 0;
	
	cin >> n >> a;
	for (int i = 0; i < n; i++) {
		cin >> x;
		ssum += x;
	}
	if (ssum % a != 0 || ssum / n != a) { cout << "NO" << endl; }
	else { cout << "YES" << endl; }
	return 0;
}