nclude<bits/stdc++.h>
using namespace std;
signed main(){
  int a;
  double b[100000],d,c=0;
  cin>>a;
  for(int i=0;i<a;i++){
    cin>>b[i];
  }
  sort(b,b+a);
  for(int i=0;i<a;i++){
    if(i==0) c=c+b[i];
    else{ 
      c=(c+b[i])/2;
    }
  }
  cout<<c<<"\n";
}
