#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  cin >> n;
  int v[100];
  for (int i = 0; i < n; i++) {
    cin >> v[i];
  }
  sort(v, v + n);
  for (int i = 0; i < n - 1; i++) {
    int d = v[i] + v[i + 1];
    double x = d / 2.0;
    v[i + 1] = x;
    cout << fixed << setprecision(10);
  }
  cout << fixed << setprecision(10);
  cout << v[n - 1] << endl;
  return 0;
}
