#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];
	}
	h = (ll)(sum / n);
	
	(a == h) && (cout << "YES" << endl);
	(a != h) && (cout << "NO" << endl);
	return 0;
}