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