#include <bits/stdc++.h>
using namespace std;
int main() {
  int N;
  cin >> N;
  vector<int> _v(N);
  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;
}
