#include <cstdio>
#include <iostream>
#include <algorithm>
using namespace std;
int main() {

 int n;
 double a[211111];

 scanf("%d", &n);

 for (int i = 0; i < n; i++)
  scanf("%lf", a + i);
 
 sort(a, a + n);
 
 for (int i = 1; i < n; i++)
  a[i] = (a[i] + a[i - 1]) / 2;

 printf("%.3lf", a[n - 1]);

 return 0;
}