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

#define rep(i, a, b) for(int i = a; i < (b); ++i)
#define all(x) begin(x), end(x)
#define sz(x) (int)(x).size()
#define pb push_back
typedef long long ll;
typedef pair<int, int> pii;
typedef vector<int> vi;

int main() {
	cin.tie(0)->sync_with_stdio(0);
    int n;
    cin >> n;
    vector<ll> a(n), b(n);
    for(int i = 0; i < n; i++)
        cin >> a[i];
    for(int i = 0; i < n; i++)
        cin >> b[i];

    long double best = 0;
    function<void(int, int, ll)> go = [&](int i, int size, ll sum) {
        if(size)
            best = max(best, (long double)(sum+a[size-1])/size);
        if(i == n)
            return;
        go(i+1, size, sum);
        go(i+1, size+1, sum+b[i]);
    };
    go(0, 0, 0);
    cout << fixed << setprecision(10) << best << "\n";
}