#include<iostream>
#include<algorithm>

using namespace std;
#define int long long

signed main(){

   int n, a;
   cin>> n>> a;
   int x[n];
   for(int i=0; i<n; i++) cin>> x[i];

   int s=0;
   for(int i=0; i<n; i++) s+=x[i];
   if(s==a*n){
      cout<< "YES"<< endl;
   }else{
      cout<< "NO"<< endl;
   }

   return 0;
}