#include <bits/stdc++.h>
using namespace std;

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

}