
#include <algorithm>
#include <iostream>
using namespace std;

int main()
{
  int N;
  cin >> N;
  vector<int> _v;
  auto * const v = &_v[0];
  for (int i = 0; i < N; ++i)
    cin >> v[i];
  sort(v, v + N);
  double den = 2.;
  double sum = 0.;
  for (int i = N - 1; 1 <= i; --i)
  {
    v[i] /= den;
    sum += v[i];
    den *= 2.;
  }
  v[0] /= (den/2.);
  sum += v[0];
  cout << sum;
  return 0;
}
