#include <bits/stdc++.h>
using namespace std;

int main(){
  int n; cin >> n;
  double v[n],c;
  for (int i=0;i<n;i++)cin >> v[i];
  sort(v,v+n);
  c = v[0];
  for (int i=1;i<n;i++)c = (c + v[i])/2.0;
  cout << c << endl;
}