#include <iostream>
#include <cstdio>

using namespace std;

int main() {
	int n, a;
	long long x;
	long long sum = 0;

	cin >> n >> a;
	for (int i = 0; i < n; i++) {
		cin >> x;
		sum += x;
	}
	double avg = (double) sum / n;

	cout << (avg == a ? "YES" : "NO") << endl;
	return 0;
}