#include <bits/stdc++.h>
struct greaters {
  bool operator()(const long& a, const long& b) const { return a > b; }
};
using namespace std;
const int N = 200050;
const int mod = 1e9 + 7;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  ;
  int tcase = 1, cas = 0;
  while (tcase--) {
    int n;
    cin >> n;
    vector<double> v;
    queue<double> q;
    for (int i = 0; i < n; i++) {
      double a;
      cin >> a;
      v.push_back(a);
    }
    sort(v.begin(), v.end());
    for (int i = 0; i < n; i++) q.push(v[i]);
    for (int i = 0; i < n - 1; i++) {
      double x = q.front();
      q.pop();
      double y = q.front();
      q.pop();
      x = (x + y) / 2.0;
      q.push(x);
    }
    cout << q.front() << '\n';
  }
  return 0;
}
