//No.476 正しくない平均
#include<iostream>
using namespace std;
int main()
{
	long long int n, a;
	cin >> n >> a;
	long long int num=0;
	long long int tmp_num;
	for (int i = 0; i < n; i++) {

		cin >> tmp_num;
		num += tmp_num;
	}
	if (num / n == a)cout << "YES" << endl;
	else cout << "NO" << endl;
	return 0;
}