#include <bits/stdc++.h>

using namespace std;

int main() {
	int n, a;
	int x[20];
	int sum = 0;
	cin >> n >> a;
	for (int i = 0; i < n; i++) {
		cin >> x[i];
		sum += x[i];
	}
	if ((double)sum / n == (double)a) {
		cout << "YES" << endl;
	} else {
		cout << "NO" << endl;
	}
}