#include <iostream>
using namespace std;
int main(void) {
	int n, x;
	double a;
	cin >> n >> a;
	long long sum = 0;
	for (int i = 0; i < n; ++i) {
		cin >> x;
		sum += x;
	}
	double ans = sum / (double)n;
	cout << (ans == a ? "YES" : "NO") << endl;
	return 0;
}