N = int(input())

M = int(input())

A = list(map(int, input().split()))

a = sum(A)

ans = 0

from math import gcd

P = 10 ** 9 + 7

for b in map(int, input().split()):
    
    x = 0
    
    for i in A:
        
        g = gcd(i, b)
        
        x -= b - g
        
    x += a * (b + 1)
    
    ans += x
    
    ans %= P
    
print(ans)