#include <bits/stdc++.h>
using namespace std;
using lint = long long int;
int main() {
  int n;
  cin >> n;
  double* v;
  v = new double[n];
  for (int i = 0; i < n; i++) {
    cin >> v[i];
  }
  sort(v, v + n, [](double const& l, double const& r) { return left > right; });
  double val = v[n - 1];
  for (int i = n - 2; i >= 0; i--) {
    val = (val + v[i]) * 0.5;
  }
  cout << val;
  return 0;
}
