#include <bits/stdc++.h>
#define INF 990000000
//17
using namespace std;

int main() {
long long int n,a;
cin>>n>>a;
long long int res=0;
for(int i=1;i<=n;i++){
long long int tem=0;
cin>>tem;
res+=tem;
}
if(res%n==0 && (res/n)*n==a*n)
cout <<"YES"<<endl;
else
cout <<"NO"<<endl;









}