#pragma region header
#include <bits/stdc++.h>
using namespace std;
// #include <atcoder/all>
// using namespace atcoder;

/* alias */
using ull = unsigned long long;
using ll = long long;
using pii = pair<int, int>;
using pll = pair<ll, ll>;
using vi = vector<int>;
using vll = vector<long long>;
using vd = vector<double>;
using vs = vector<string>;
using vb = vector<bool>;
using vpii = vector<pair<int, int>>;
using vpll = vector<pair<ll, ll>>;
using vvi = vector<vector<int>>;
using vvll = vector<vector<long long>>;
using vvd = vector<vector<double>>;
using vvs = vector<vector<string>>;
using vvb = vector<vector<bool>>;
template<typename T> using min_priority_queue = priority_queue<T, vector<T>, greater<T>>;

/* define */
#define MOD 998244353
// #define MOD 1000000007
#define INF (1LL << 60)
#define inf (1 << 28)
#define elif else if
#define pb push_back
#define pf push_front
#define fi first
#define se second
#define all(obj) (obj).begin(), (obj).end()
#define YESNO(bool) cout << (bool ? "YES\n" : "NO\n")
#define YesNo(bool) cout << (bool ? "Yes\n" : "No\n")
#define yesno(bool) cout << (bool ? "yes\n" : "no\n")
template<class T> bool chmax(T &a, const T &b) {if(a<b){ a=b; return 1;} return 0;}
template<class T> bool chmin(T &a, const T &b) {if(b<a){ a=b; return 1;} return 0;}
#define debug(x) cerr << #x << ":" << x << "\n";

/* REP macro */
#define reps(i, a, n) for(int i = (a); i < (n); i++)
#define rep(i, n) reps(i, 0, (n))
#define rrep(i, n) reps(i, 1, (n + 1))
#define repd(i, n) for(int i = (n - 1); i >= 0; i--)
#define rrepd(i, n) for(int i = (n); i >= 1; i--)
#define fore(i, a) for(auto &i: a)

/* vector */
template<class T> T vmax(vector<T> &array){ T ret = array[0]; for(T a: array) chmax(ret, a); return ret; }
template<class T> T vmin(vector<T> &array){ T ret = array[0]; for(T a: array) chmin(ret, a); return ret; }
template<class T> T sum(vector<T> &array){ T ret = 0; for(T a:array) ret += a; return ret; }
template<class T> void list_set(vector<T> &array){ sort(all(array)); array.erase(unique(all(array)),array.end()); }
template<class T> T bisect_left(vector<T> &array, T key){ return lower_bound(all(array),key) - array.begin(); }
template<class T> T bisect_right(vector<T> &array, T key){ return upper_bound(all(array),key) - array.begin(); }

/* string */
ll string_to_ll(string n){ ll ret = 0, k = 1; while(n.length() > 0){ ret += k * (n.back() - '0'); n.pop_back(); k *= 10; } return ret; }
string ll_to_string(ll n){ string ret = ""; while(n > 0){ ret.pb((n % 10) + '0'); n /= 10; } reverse(all(ret)); return ret; }

struct popopo{ popopo(){ cin.tie(0); ios::sync_with_stdio(0); cout << fixed << setprecision(15); }; } popopoppo;

#pragma endregion header    

#define double long double

int main(){


    ll N; cin >> N;
    vector<double> A(N); for(int i = 0; i < N; i++) cin >> A[i];
    vector<double> B(N); for(int i = 0; i < N; i++) cin >> B[i];
    

    auto solve = [&](double x) -> double {
        double ret = 0.0;
        rep(i, N){
            ret += A[i] / (1.0 + x) + B[i] * (1 + x);
        }
        return ret;
    };


    double zero = solve(0);
    double ng = 1;
    while(true){
        if(zero < solve(ng)) break;
        ng *= 10;
    }

    double ok = 0;


    while(abs(ok - ng) > 1e-12){

        double c1 = solve((ok * 2.0 + ng) / 3.0);
        double c2 = solve((ok + ng * 2.0) / 3.0);

        if(c1 > c2){
            ok = (ok * 2.0 + ng) / 3.0;
        }else{
            ng = (ok + ng * 2.0) / 3.0;
        }

    }

    cout << solve(ok) << endl;

}