from math import gcd
def solve():
    mod = 10**9+7
    N = int(input())
    M = int(input())
    A = list(map(int, input().split()))
    B = list(map(int, input().split()))
    ans = (sum(B)+M)*sum(A)%mod
    for a in A:
        for b in B:
            g = gcd(a,b)
            ans -= (b//g)*(b//g-1)*g*g//b
    return ans%mod
print(solve())