#include <bits/stdc++.h>
int main() {
  using namespace std;
  cin.tie(nullptr);
  ios::sync_with_stdio(false);
  int N;
  cin >> N;
  vector<int> v(N);
  for (auto &e : v) {
    cin >> e;
  }
  sort(v.begin(), v.end());
  cout << accumulate(v.begin() + 1, v.end(), 1.0 * v[0], [](int a, int b) {
    return (a + b) / 2.0;
  }) << "\n";
}
