#include <bits/stdc++.h>
using namespace std;

int main() {
  int N;
  cin >> N;
  int v[N];
  for (int i = 0; i < N; i++) cin >> v[i];
  sort(v, v + N);
  double c = v[0];
  for (int i = 1; i < N; i++) c = (c + v[i]) / 2;
  cout << c << endl;
  return 0;
}
