#include <iostream>
using namespace std;
int main(){
	int n,a,sum=0;
	cin>>n>>a;
	int x[n];
	for(int i=0;i<n;i++){
		cin>>x[i];
		sum+=x[i];
	}
	if(sum/n==a && sum%n==0) cout<<"YES"<<endl;
	else cout<<"NO"<<endl;
	return 0;
}