#include <bits/stdc++.h>
using ll = long long;
using namespace std;
int main() {
  cin.tie(0);
  ios::sync_with_stdio(false);
  cout << setprecision(1000) << fixed;
  int n;
  cin >> n;
  int* v = new int[n];
  for (int i = 0; i < n; i++) {
    cin >> v[i];
  }
  sort_heap(v, v + n);
  double ans = v[0];
  for (int i = 1; i < n; i++) {
    ans = (ans + v[i]) / 2;
  }
  cout << ans << endl;
  delete[] v;
  return 0;
}
