#include <bits/stdc++.h>
using namespace std;
const long long mod = 1e9 + 7;
using ll = long long;
using pii = pair<int, int>;
using pll = pair<ll, ll>;
unsigned long long gcd(unsigned long long a, unsigned long long b) {
  return b ? gcd(b, a % b) : a;
}
unsigned long long lcm(unsigned long long a, unsigned long long b) {
  return a / gcd(a, b) * b;
}
int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  cout << fixed << setprecision(8);
  int n;
  cin >> n;
  vector<int> v(n);
  for (int i = 0, i_len = (n); i < i_len; i++) {
    cin >> v[i];
  }
  sort((v).begin(), (v).end());
  double ans = 0;
  for (int i = 0, i_len = (n); i < i_len; i++) {
    ans += (v[i] + ans) / 2;
  }
  cout << ans << endl;
  return 0;
}
