#include <bits/stdc++.h>

using namespace std;

typedef unsigned long long ull;
typedef long long ll;

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