# https://yukicoder.me/problems/no/3604

def solve(N, cum_a_list, cum_b_list, v):

    max_r_list = [0.0] * N
    max_r = -float("inf")
    for r in reversed(range(N)):
        x = cum_a_list[r] - v * cum_b_list[r]
        max_r = max(x, max_r)
        max_r_list[r] = max_r

    min_r = 0.0
    for k in range(N):
        if not max_r_list[k] >= min_r:
            return False

        x = cum_a_list[k] - v * cum_b_list[k]
        min_r = min(min_r, x)
    return True

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

    cum_a_list = [0] * N
    a = 0
    for i in range(N):
        a += A[i]
        cum_a_list[i] = a
    cum_b_list = [0] * N
    b = 0
    for i in range(N):
        b += B[i]
        cum_b_list[i] = b

    low = 0.0
    high = float(sum(A))
    while high - low > 10 ** (-6):
        mid = (high + low) / 2.0
        if solve(N, cum_a_list, cum_b_list, mid):
            low = mid
        else:
            high = mid
    print(low)





if __name__ == "__main__":
    main()