#include <iostream>
#include <vector>
#include <utility>
#include <map>
#include <algorithm>
#include <queue>
#include <cmath>

using namespace std;

int main() {
	
   int n;
   cin >> n;
   vector<long double> v(n);

   for(int i=0;i<n;i++){
      cin >> v[i]; 
   }
   
   sort(v.begin(), v.end())
   
   long double ans = v[0];
   for(int i=1;i<n;i++){
    ans = (ans +v[i]) / 2; 
   } 

  cout << ans << endl;
}

