#include <iostream>
using namespace std;
using ll = long long;
int main()
{
ll n, a;
cin >> n >> a;
ll expe = n*a;
ll sum = 0;
for(int i = 0; i < n; i++)
{
ll x;
cin  >> x;
sum += x;
}
if(expe == sum){
cout << "YES" << endl;
} else {
cout << "NO" << endl;
}
return 0;
}