import sys
from math import gcd
def I(): return int(sys.stdin.readline().rstrip())
def LI(): return list(map(int,sys.stdin.readline().rstrip().split()))


N,M = I(),I()
A,B = LI(),LI()
mod = 10**9+7
ans = 0
for i in range(N):
    a = A[i]
    for j in range(M):
        b = B[j]
        g = gcd(a,b)
        ans += a*b+a-b+g
        ans %= mod

print(ans)