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

signed main(){
	int n, a;
	cin >> n >> a;
	int mean = a * n;
	int sum = 0;
	
	int b;
	for(int i = 0; i < n; i++){
		cin >> b;
		sum += b;
	}
	
	cout << (mean == sum ? "YES" : "NO") << endl;
}