#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  cin >> n;
  vector<int> a(n);
  for (int i = 0; i < (n); ++i) {
    cin >> a.at(i);
  }
  sort(a.begin(), a.end());
  for (int i = 0; i < n - 1; i++) {
    double div = 0;
    div = (a.at(0) + a.at(1)) / 2;
    a.erase(a.begin() + 1);
    a.erase(a.begin());
    a.push_back(div);
    sort(a.begin(), a.end());
  }
  cout << a.at(0);
}
