#include <algorithm>
#include <iomanip>
#include <iostream>
#include <vector>

using namespace std;

int main() {
  int n;
  cin >> n;
  vector<int> bonus(n);
  for(auto& x: bonus) cin >> x;
  vector<int> v(n);
  for(auto& x: v) cin >> x;
  sort(v.rbegin(), v.rend());
  double ret = 0;
  int amt = 0;
  for(int i = 0; i < n; i++) {
    amt += v[i];
    ret = max(ret, (amt + bonus[i]) / double(i+1));
  }
  cout << fixed << setprecision(39) << ret << "\n";
}