#include<iostream>
#include<algorithm>

int main(){
  int n;
  int i;
  int v[n];
  double w[n];
  std::cin >> n;
  for(i=0;i<n;i++){
    std:cin >> v[i];
    w[i] = (double)v[i];
  }
  std::sort(v,v+n);
  
  for(i=0;i<n-1;i++){
   w[i+1] = (w[i] + w[i+1])/2;
  }
  
  std::cout >> w[n];
}