#include <bits/stdc++.h>
using namespace std;
template <class T>
inline void chmax(T &ans, T t) {
  if (t > ans) ans = t;
}
template <class T>
inline void chmin(T &ans, T t) {
  if (t < ans) ans = t;
}
int main() {
  cout << fixed;
  cout << setprecision(11);
  int n;
  cin >> n;
  vector<long long> v(n);
  for (long long i = 0; i < n; i++) cin >> v[i];
  if (n == 2) {
    double t = v[0] + v[1];
    printf("%lf\n", t / 2.0);
    return 0;
  }
  sort(v.begin(), v.end());
  double p = (v[0] + v[1]) / 2;
  for (int i = 2; i < n; ++i) {
    p = (p + v[i]) / 2.0;
  }
  cout << p << endl;
}
