#include <bits/stdc++.h>
using namespace std;

int main() {
  int N;
  cin >> N;
  
  double A[N];
  for (int i = 0; i < N; i++) cin >> A[i];
  
  sort(A.begin(), A.end());
  
  double ans = (A[0] + A[1]) / 2;
  for (int i = 2; i < N; i++) {
    ans += (ans + A[i]) / 2; 
  }
  
  cout << fixed << setprecision(10) << ans << endl;

}