#include <bits/stdc++.h>
using namespace std;
double a[110], res = 0;
int main() {
  int i, n;
  cin >> n;
  for (i = 0; i < n; i++) {
    cin >> a[i];
  }
  sort(a, a + n);
  res = a[0];
  for (i = 1; i < n; i++) {
    res += (res + a[i]) / 2;
  }
  cout << res << endl;
}
