#include <bits/stdc++.h>
using namespace std;
int main() {
  long long n;
  cin >> n;
  vector<long long> numbers(n);
  for (auto &i : numbers) cin >> i;
  sort(numbers.begin(), numbers.end());
  long double ans = numbers[0];
  for (auto i : numbers) {
    ans = (ans + i) / 2;
  }
  cout << ans << endl;
  return 0;
}
