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

def f(A,B):
    ret = 0
    a,b = 0,0
    for i in range(N):
        a += A[i]
        b += B[i]
        ret = max(ret, a/b)
    return ret

ans = min(f(A,B), f(A[::-1], B[::-1]))
print(ans)