from itertools import accumulate
n = int(input())
a = list(accumulate(map(int, input().split()), initial=0))
b = list(accumulate(map(int, input().split()), initial=0))
l = 0
r = a[n] + 1.0
while True:
    c = (l + r) / 2
    if not l < c < r:
        break
    d = [x - c * y for x, y in zip(a, b)]
    mns = d[:]
    for i in range(n):
        mns[i+1] = min(mns[i], d[i])
    mx = d[n]
    ok = True
    for i in range(n)[::-1]:
        if mns[i] > mx:
            ok = False
            break
        mx = max(mx, d[i])
    if ok:
        l = c
    else:
        r = c
print(f'{l:.10f}')