#include <iostream>
using namespace std;

int main() {
	long long n, a, t=0;
	cin >> n >> a;
	long long x[10];
	for(int i=0;i<n;i++){
		cin >> x[i];
		t += x[i];
	}
	if(n*a==t)
		cout << "YES" << endl;
	else
		cout << "NO" << endl;
}