#include <bits/stdc++.h>
using namespace std;
int main()
{
  
  int n;
  cin>>n;
  double arr[n];
  for ( int i=0;i<n;i++)
    	cin>>arr[i];
 	sort ( arr,arr+n);
  for ( int i=0;i<n-1;i++)
    arr[i+1]=(arr[i]+arr[i+1])/2;
  cout<<arr[n-1];
}