#include <bits/stdc++.h>
using namespace std;
vector<int> v;
int main() {
  int N;
  cin >> N;
  for (int i = 0; i < N; i++) {
    int a;
    cin >> a;
    v.push_back(a);
  }
  sort(v.begin(), v.end());
  double ans = v[0];
  for (int i = 1; i < N; i++) {
    ans = (ans + v[i]) / 2.0;
  }
  printf("%lf\n", ans);
  return 0;
}
