#include <iostream>
using namespace std;
#define MAX_INDEX 10
typedef long long ll;

int main() {
	int n;ll a;
	cin >> n >> a;

	int i;
	ll x[MAX_INDEX], sum=0, h;
	for (i = 0;i<n; i++) {
		cin >> x[i];
		sum += x[i];
	}
	if (sum % n){
        cout << "NO" << endl;
        return 0;
    }
    h = sum / n;

	if (a == h) {
        cout << "YES" << endl;
    }
	if (a != h) {
        cout << "NO" << endl;
    }
	return 0;
}