#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  cin >> n;
  vector<int> v(n);
  for (int i = 0; i < n; ++i) cin >> v[i];
  sort(v.begin(), v.end());
  double ans = v[0];
  for (int v : v) {
    ans = (ans + v) / 2.0;
  }
  cout << ans << endl;
  return 0;
}
