#include <bits/stdc++.h>
using namespace std;
template <typename T>
int partion(vector<T>& a, int l, int r) {
  int pivot = a[l];
  int less[r - l + 1], greater[r - l + 1];
  int i = 0, j = 0;
  for (int k = l; k < r; ++k) {
    if (a[k] < pivot) {
      less[i++] = a[k];
    } else {
      greater[j++] = a[k];
    }
  }
  for (int k = 0; k < i; ++k) {
    a[l + k] = less[k];
  }
  for (int k = 0; k < j; ++k) {
    a[l + i + k] = greater[k];
  }
  return l + i;
}
template <typename T>
void quick_sort(vector<T>& a, int l = 0, int r = -1) {
  if (r < 0) r = a.size();
  if (r - l <= 1) return;
  int m = partion(a, l, r);
  if (l == m || m == r) return;
  quick_sort(a, l, m);
  quick_sort(a, m, r);
}
int main() {
  int n;
  cin >> n;
  vector<double> a(n);
  for (auto& ai : a) cin >> ai;
  quick_sort(a);
  double ans = a[0];
  for (int i = 1; i < n; ++i) (ans += a[i]) /= 2.0;
  cout << fixed << ans << endl;
}
