N = int(input())
A = list(map(int, input().split()))
B = list(map(int, input().split()))

INF = 1<<60

def func(x):
    C = [a/x for a in A]
    D = B[:]
    cum = [0]
    for i in range(N):
        cum.append(cum[-1]+C[i]-D[i])
    L = [cum[0]]
    for n in cum[1:]:
        L.append(min(L[-1], n))
    R = [cum[-1]]
    for n in cum[::-1][1:]:
        R.append(max(R[-1], n))
    R = R[::-1]
    for i in range(N):
        if R[i+1]-L[i] <= 0:
            return True
    return False

left = 0
right = 10**16
for _ in range(100):
    mid = (left+right)/2
    if not func(mid):
        left = mid
    else:
        right = mid

print(right)