from math import gcd

n = int(input())
m = int(input())
A = list(map(int,input().split()))
B = list(map(int,input().split()))
mod = 1_000_000_007

ans = 0
for a in A:
    if(a==0):
        continue
    for b in B:
        gcd_num = gcd(a,b)
        ans += (a*(b+1))%mod - (b-gcd_num)
        ans %= mod

print(ans)