import sys
# input = lambda :sys.stdin.readline()[:-1]
ni = lambda :int(input())
na = lambda :list(map(int,input().split()))
yes = lambda :print("yes");Yes = lambda :print("Yes");YES = lambda : print("YES")
no = lambda :print("no");No = lambda :print("No");NO = lambda : print("NO")
#######################################################################
"""

(1) a[i] = 1


0 <= s[n] - 2s[i] <= 1


a[r] - a[l] >= xb[r] - xb[l]

a[r] - xb[r] >= a[l] - xb[l]
0 1 3 6
0 3 5 6

0 -2 -2 0

"""
def check(mid):
    f = [-1] * (n + 1)
    g = [-1] * (n + 1)
    f[0] = a[0] - mid * b[0]
    g[n] = a[-1] - mid * b[-1]
    for i in range(n):
        f[i+1] = min(f[i], a[i+1] - mid * b[i+1])
    for i in range(n-1, -1, -1):
        g[i] = max(g[i+1], a[i] - mid * b[i])
    # print(mid, f, g)
    return all(f[i] <= g[i+1] for i in range(n))

n = ni()
a = [0] + na()
b = [0] + na()
for i in range(n):
    a[i+1] += a[i]
    b[i+1] += b[i]


# check(1)
ok = 0
ng = 10 ** 18


for _ in range(200):
    mid = (ok + ng) / 2

    
    # print(mid, f, g)
    if check(mid):
        ok = mid
    else:
        ng = mid

print(ok)