#include <iostream>

using namespace std;

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