#include <bits/stdc++.h>
int main() {
  int N;
  std::vector<int> v;
  std::cin >> N;
  for (int i = 0; i < N; i++) {
    int temp;
    std::cin >> temp;
    v.push_back(temp);
  }
  std::sort(v.begin(), v.end());
  double resa = 0;
  double ave = v[0];
  for (int i = 0; i < (int)v.size() - 1; i++) {
    ave = (ave + v[i + 1]) / 2.0;
  }
  std::cout << ave << std::endl;
  return 0;
}
