#include <bits/stdc++.h>
using namespace std;
struct cww{cww(){ios::sync_with_stdio(false);cin.tie(0);}}star;
int main()
{
	int N;
	long long A;
	cin >> N >> A;
	vector<long long> vc( N );
	for( auto &x : vc )
	{
		cin >> x;
	}
	cout << ( (long double)accumulate( vc.begin(), vc.end(), 0 ) / N == A ? "YES" : "NO" ) << endl;
	return 0;
}