#include <bits/stdc++.h>
using namespace std;
#pragma GCC optimize("Ofast")
int gcd(int a, int b) { return b ? gcd(b, a % b) : a; };
int lcm(int a, int b) { return a * b / gcd(a, b); };
int month[12] = {31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
template <typename A, size_t N, typename T>
void Fill(A (&array)[N], const T &val) {
  std::fill((T *)array, (T *)(array + N), val);
};
int main() {
  cin.tie(0);
  cout.tie(0);
  ios::sync_with_stdio(false);
  int n;
  cin >> n;
  vector<double> v(n);
  for (int i = 0; i < (int)(n); i++) cin >> v[i];
  sort((v).begin(), (v).end());
  for (int i = 0; i < (int)(n); i++) {
    v[i + 1] = (v[i] + v[i + 1]) / 2;
  }
  cout << fixed << v[n - 1] << endl;
  return 0;
}
