#include <bits/stdc++.h>
using namespace std;
using P = pair<int, int>;
int main() {
  long long n;
  cin >> n;
  vector<long long> v(n);
  for (long long i = 0; i < n; i++) cin >> v[i];
  sort(v.begin(), v.end());
  long double now = 0;
  for (long long i = 0; i < n; i++) {
    if (now == 0)
      now = v[i];
    else {
      now = (now + v[i]) / 2.0;
    }
  }
  　　　cout << now << endl;
}
