#include <bits/stdc++.h>
using namespace std;
void solve() {
  int n;
  cin >> n;
  vector<double> v(n);
  for (int i = 0; i < n; i++) {
    cin >> v[i];
  }
  sort(v.begin(), v.end());
  vector<double> res;
  double maxval = 0;
  double current = 0;
  if (n == 1)
    cout << v[0] << endl;
  else if (n == 2) {
    printf("%lf", (v[0] + v[1]) / 2);
  } else {
    do {
      current = pow(2, n - 2) * v[0] + pow(2, n - 2) * v[1];
      for (int i = 2; i < n; i++) {
        current += pow(2, n - 1) * v[i];
      }
      if (maxval < current) {
        maxval = current;
        res = v;
      }
    } while (next_permutation(v.begin(), v.end()));
    maxval = res[0];
    for (int i = 1; i < n; i++) {
      maxval = (maxval + res[i]) / 2;
    }
    printf("%lf", maxval);
  }
}
int main() {
  solve();
  return 0;
}
