#include <bits/stdc++.h>
using namespace std;
double pi = 3.141592653589793;
long long mod = 1000000007;
long long INF = 1000000001;
int intmax = 2147483647;
int intmin = -2147483648;
long long llmax = 9223372036854775807;
long long llmin = -9223372036854775807;
int main() {
  int n;
  cin >> n;
  vector<long long> v(n);
  for (int i = 0; i < n; i++) {
    cin >> v[i];
  }
  sort(v.begin(), v.end());
  for (int i = 0; i < n; i++) {
    cout << v[i];
  }
  double ans;
  ans = v[0];
  for (int i = 0; i < n; i++) {
    ans = (ans + v[i]) / 2;
  }
  cout << ans << endl;
  return 0;
}
