#include <bits/stdc++.h>
using namespace std;
using ll = long long;
int main() {
  ll N;
  cin >> N;
  vector<double> v(N);
  for (auto &&e : v) {
    cin >> e;
  }
  sort(v.begin(), v.end());
  double ans = v[0];
  for (ll i = 1; i < N; ++i) {
    ans = (ans + v[i]) / 2;
  }
  cout << ans << endl;
}
