#include <bits/stdc++.h>
using namespace std;
vector<string> split(const string& str, char delimiter) {
  vector<string> ret;
  string tmp = "";
  for (auto c : str) {
    if (c != delimiter) {
      tmp.push_back(c);
    } else {
      ret.push_back(tmp);
      tmp = "";
    }
  }
  ret.push_back(tmp);
  return ret;
}
template <typename T>
void sortAsc(vector<T>& v) {
  sort(v.begin(), v.end(), less<T>());
}
template <typename T>
void sortDesc(vector<T>& v) {
  sort(v.begin(), v.end(), greater<T>());
}
int main() {
  int N;
  cin >> N;
  ;
  vector<double> v(N);
  for (int i = 0; i < N; ++i) {
    cin >> v[i];
  };
  sortDesc(v);
  while (v.size() > 1) {
    v[0] = (v[0] + v[1]) / 2.0;
    v.erase(v.begin() + 1);
  }
  cout << (v[0]) << endl;
  ;
  return 0;
}
