#include <bits/stdc++.h>
using namespace std;
using P = pair<double, double>;
int main () {
    int N;
    cin >> N;
    vector<P> A(N);
    for (auto& [a, b] : A) {
        cin >> a;
    }
    for (auto& [a, b] : A) {
        cin >> b;
    }
    double ans = 0;
    for (auto [a, b] : A) {
        if (a <= b) {
            ans += a + b;
        } else {
            ans += 2 * sqrt(a * b);
        }
    }
    cout << setprecision(20) << ans << endl;
}