from math import gcd

def sum_of_floor(n, p, q):
    s = 0
    t = gcd(p, q)
    p, q = p // t, q // t
    z = 1
    while q > 0 and n > 0:
        t = p // q
        s = s + z * t * n * (n + 1) // 2
        p = p - q * t
        t = n // q
        s = s + z * p * t * (n + 1) - z * t * (p * q * t + p + q - 1) // 2
        n = n - q * t
        t = (n * p) // q
        s = s + z * t * n
        n = t
        p, q = q, p
        z = -z
    return s

n = int(input())
m = int(input())
a = list(map(int, input().split()))
b = list(map(int, input().split()))
ans = 0
for i in range(n):
    for j in range(m):
        ans += sum_of_floor(b[j], a[i], b[j]) * 2
print(ans % (10 ** 9 + 7))