#include <bits/stdc++.h>
using namespace std;
using Graph = vector<vector<int>>;
const int dx[4] = {1, 0, -1, 0};
const int dy[4] = {0, 1, 0, -1};
int main() {
  int n;
  cin >> n;
  std::vector<double> v(n);
  for (auto& i : v) std::cin >> i;
  ;
  sort(v.begin(), v.end());
  double sum = (v[0] + v[1]) / 2;
  for (int i = (int)(2); (i) <= (int)(n); i++) {
    sum = (sum + v[i]) / 2;
  }
  cout << sum;
}
