#!/usr/bin/env PyPy3

from collections import Counter, defaultdict, deque
import itertools
import re
import math
from functools import reduce
import operator
import bisect
from heapq import *
import functools
mod=998244353

import sys
input=sys.stdin.readline

n = int(input())
a = list(map(int,input().split()))
b = list(map(int,input().split()))
flg = [0] * n
ma = 0
for i in range(n):
    if ma < a[i] / b[i]:
        ma = a[i] / b[i]
        flg[i] = 1
ans = 0
l = -1
now = 1
def f(x,l,r):
    res = 0
    for i in range(l,r):
        res += a[i] / x + b[i] * x
    return res

for i in range(n):
    if flg[i]:
        if l == -1:
            l = i
        else:
            high = 10 ** 5
            low = now
            while high - low > (10 ** (-12)):
                l1 = low + (high - low) / 3
                l2 = high - (high - low) / 3
                if f(l1,l,i) > f(l2,l,i):
                    low = l1
                else:
                    high = l2
            ans += f((high+low)/2,l,i)
            l = i
            now = (high+low)/2 
high = 10 ** 5
low = now

while high - low > (10 ** (-12)):
    l1 = low + (high - low) / 3
    l2 = high - (high - low) / 3
    if f(l1,l,n) > f(l2,l,n):
        low = l1
    else:
        high = l2
ans += f((high+low)/2,l,n)

print(ans)