#include <cstdio>
#include <algorithm>
#include <iostream>
#include <vector>

using namespace std;

int main(void){
  int n;
  double a,x,res;
  cin>>n>>a;
  res=0;
  for(int i=0;i<n;i++){
    cin>>x;
    res+=x;
  }
  if(res/n==a)cout<<"YES"<<endl;
  else cout<<"NO"<<endl;
  return 0;
}