#include <bits/stdc++.h>
using namespace std;
int a[50];
int main() {
  int n;
  cin >> n;
  for (int i = 0; i < n; ++i) {
    cin >> a[i];
  }
  sort(a, a + n);
  double ans = a[0];
  for (int i = 1; i < n; ++i) {
    ans = (ans + a[i]) / 2;
  }
  cout << ans << endl;
}
