#include <bits/stdc++.h>
using namespace std;

int main()
{
	int n;
	long long a;
	cin >> n >> a;
	long long sum = 0;
	for( int i = 0; i < n; i++ ) {
		int aa;
		cin >> aa;
		sum += aa;
	}

	string ans = "NO";
	if( a * n == sum ) ans = "YES";

	cout << ans << endl;
}