#include <bits/stdc++.h>
using namespace std;
int32_t main(void) {
  ios::sync_with_stdio(0);
  cin.tie(0);
  ;
  long long int n;
  cin >> n;
  double x = 0;
  vector<long long int> a(n);
  for (long long int i = 0; i < n; i++) cin >> a[i];
  sort(a.begin(), a.end(), greater<long long int>());
  for (long long int i = 0; i < n; i++) x = (x + a[i]) / 2;
  cout << x;
}
