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

def Floor_sum(N,M,A,B):
    ANS=0

    if A>=M:
        ANS+=N*(N-1)//2*(A//M)
        A%=M
    if B>=M:
        ANS+=(B//M*N)%mod
        B%=M

    y_max=(A*N+B)//M
    x_max_divA=y_max*M-B

    if y_max==0:
        return ANS
    else:
        return ANS+Floor_sum(y_max,A,M,A*N-x_max_divA)

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 i in range(N):
    for j in range(M):
        ANS+=Floor_sum(B[j]+1,B[j],A[i],0)

print(ANS*2%mod)