#include <bits/stdc++.h>
#include <iostream>
#include <algorithm>

using namespace std;


int main() {
 double a,b[55],c;
  
  cin >> a;
  
  for(int i=0;i<a;i++)
    cin >> b[i];
  
  
  sort(b,b+a);
  
  c =b[0];
  for(int i=1;i<a;i++){
    c = (c+b[i])/2;
  }
  
  cout << c << endl;
}
    
    
