#include <bits/stdc++.h>
using namespace std;
using ll = long long;
ll solve() {
  ll N;
  cin >> N;
  vector<ll> V(N);
  for (int i = 0; i < N; i++) {
    cin >> V[i];
  }
  sort(V.begin(), V.end());
  double a = V[0];
  for (int i = 1; i < N; i++) {
    a = (a + V[i]) / 2;
  }
  return a;
}
int main() {
  cout.precision(15);
  auto ans = solve();
  cout << ans << "\n";
  return 0;
}
