#include <bits/stdc++.h>
using namespace std;

int main(){
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);

    int N; cin >> N;
    vector<long long> A(N),B(N);
    for(auto &a : A) cin >> a;
    for(auto &b : B) cin >> b;

    double low = 0,high = 1001001001;
    for(int t=0; t<70; t++){
        double mid = (high+low)/2;
        vector<double> D(N);
        for(int i=0; i<N; i++) D.at(i) = A.at(i)-B.at(i)*mid;
        vector<double> R(N);
        double big = 0;
        for(int i=N-1; i>=0; i--){
            R.at(i) = big;
            big += D.at(i),big = max(0.0,big);
        }
        big = 0;
        bool ok = false;
        for(int i=0; i<N; i++){
            double now = D.at(i)+R.at(i)+big;
            if(now <= 0){ok = true; break;}
            big += D.at(i),big = max(0.0,big);
        }

        if(ok) high = mid;
        else low = mid;
    }
    cout << fixed << setprecision(20) << high << "\n";
}