#include <bits/stdc++.h>
using namespace std;
template <typename T>
void swapp(T &a, T &b) {
  T temp = a;
  a = b;
  b = temp;
}
void sort(int n, double a[]) {
  for (int i = 0; i < n - 1; i++)
    for (int j = i + 1; j < n; j++)
      if (a[j] < a[j - 1]) swapp(a[j], a[j - 1]);
}
int main() {
  int n;
  cin >> n;
  if (n == 0) return 0;
  double a[n];
  for (int i = 0; i < n; i++) cin >> a[i];
  sort(n, a);
  double answer = a[0];
  for (int i = 1; i < n; i++) answer = (answer + a[i]) / 2.0;
  cout << answer;
  return 0;
}
