#include <iostream>
#include <algorithm>
#include <cstdio>
#include <string>

#define ll long long

using namespace std;

int main(){

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