from math import gcd

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

mod = 10**9+7
res = 0

for j in range(M):
    for i in range(N):
        g = gcd(A[i],B[j])

        res += A[i] * (B[j]+1)
        res %= mod

        res -= (B[j]-g)
        res %= mod

print(res)