#include <bits/stdc++.h>
using namespace std;
template <class T>
inline bool chmax(T &a, T b) {
  if (a < b) {
    a = b;
    return true;
  }
  return false;
}
template <class T>
inline bool chmin(T &a, T b) {
  if (a > b) {
    a = b;
    return true;
  }
  return false;
}
double ans;
int main() {
  int N;
  cin >> N;
  vector<double> v(N);
  for (int i = 0; i < N; i++) cin >> v[i];
  sort(v.begin(), v.end(), greater<double>());
  double factor = 2;
  for (int i = 0; i < N; i++) {
    factor /= 2.0;
    ans += factor * v[i];
  }
  cout << ans << endl;
  return 0;
}
