#include <bits/stdc++.h>
using namespace std;
int main() {
  int N;
  double v[N];
  cin >> N;
  for (int i = 0; i < N; i++) cin >> v[i];
  sort(v, v + N);
  double ans = v[0];
  for (int i = 1; i < N; i++) ans = (ans + v[i]) / 2.0;
  cout << ans << endl;
}
