#include <bits/stdc++.h>
using namespace std;
int n, x;
std::vector<int> v;
int main(int argc, char const *argv[]) {
  cin >> n;
  for (int i = 0; i < n; i++) {
    cin >> x;
    v.push_back(x);
  }
  sort(v.begin(), v.end());
  double ans = (double)(v[0] + v[1]) / 2.0;
  for (int i = 2; i < v.size(); i++) ans = (ans + (double)v[i]) / 2.0;
  return 0;
}
