#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  cin >> n;
  double a[n];
  for (int i = 0; i < n; i++) {
    cin >> a[i];
  }
  sort(a, a + n);
  reverse(a, a + n);
  double sum = a[0];
  for (int i = 1; i < n; i++) {
    sum = (sum + a[i]) / 2;
  }
  cout << sum << endl;
}
