#include <iostream>
#include <algorithm>
using namespace std;

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