#include <bits/stdc++.h>
using namespace std;
int main() {
  int N;
  cin >> N;
  int v_arr[N];
  int i;
  vector<int> ans;
  double sum;
  for (i = 0; i < N; i++) {
    cin >> v_arr[i];
  }
  sort(v_arr, v_arr + N);
  do {
    for (i = 0; i < N; i++) {
      if (i == 0) {
        sum = v_arr[i];
      }
      if (i != 0) {
        sum = (sum + v_arr[i]) / 2;
      }
    }
    ans.push_back(sum);
    sum = 0;
  } while (next_permutation(v_arr, v_arr + N));
  int max = *std::max_element(ans.begin(), ans.end());
  cout << max << endl;
  return 0;
}
