#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  long double ans;
  cin >> n;
  vector<long double> v(n);
  for (int i = 0; i < (n); i++) cin >> v.at(i);
  sort(v.rbegin(), v.rend());
  ans = v.at(0);
  for (int i = 1; i < n; i++) ans = (ans + v.at(i)) / 2;
  cout << setprecision(10) << ans;
}
