#include <bits/stdc++.h>
int main() {
  int n;
  std::cin >> n;
  std::priority_queue<int, std::vector<int>, std::greater<int> > q;
  for (int i = 0; i < n; i++) {
    int a;
    std::cin >> a;
    q.push(a);
  }
  while (q.size() >= 2) {
    int greatest = q.top();
    q.pop();
    int second_greatest = q.top();
    q.pop();
    int combined = (greatest + second_greatest) * 0.5;
    q.push(combined);
  }
  std::cout << q.top() << std::endl;
}
