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