#include <bits/stdc++.h>
using namespace std;
const long long MOD = 1000000007;
int main() {
  int n;
  cin >> n;
  vector<int> a(n);
  for (int i = 0; i < int(n); i++) cin >> a[i];
  sort(a.rbegin(), a.rend());
  while (a.size() > 1) {
    double x = (a[a.size() - 1] + a[a.size() - 2]) / 2;
    a.pop_back();
    a.pop_back();
    a.push_back(x);
  }
  cout << a[0] << endl;
}
