#include<iostream>
using namespace std;

int main(){
  int n,x,average=0;
  cin >> n >> x;
  int a[n],i;
  for(i=0;i<n;i++){
    cin >> a[i];
    average += a[i];
  }
  average = average / n;
  if(average == x){
    cout << "YES" << "\n";
  }
  else{
    cout << "NO" << "\n";
  }
  return 0;
}