#include <bits/stdc++.h>
using namespace std;
long long gcd(long long a, long long b) { return b != 0 ? gcd(b, a % b) : a; }
long long lcm(long long a, long long b) { return a * b / gcd(a, b); }
int main() {
  long long n;
  cin >> n;
  vector<long long> v(n);
  for (long long i = 0; i < n; i++) cin >> v[i];
  sort((v).begin(), (v).end());
  double s = 0;
  for (long long i = 0; i < n; i++) s = (s + v[i]) / 2;
  printf("%.5lf\n", s);
  return 0;
}
