import sys
import io, os
#input = io.BytesIO(os.read(0,os.fstat(0).st_size)).readline

from math import gcd

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

ANS=0
mod=10**9+7

for a in A:
    for b in B:
        ANS=(ANS+(a-1)*(b+1)+gcd(a,b)+1)%mod
print(ANS%mod)