#line 1 "a.cpp"
#include<iostream>
using namespace std;
#line 1 "/home/kotatsugame/library/math/floor_sum.cpp"
long long floor_sum(long long N,long long M,long long A,long long B)
//Sum[floor((A*i+B)/M),{i,0,N-1}]
{
	long long ans=0;
	if(A>=M)
	{
		ans+=N*(N-1)/2*(A/M);
		A%=M;
	}
	if(B>=M)
	{
		ans+=N*(B/M);
		B%=M;
	}
	long long Ym=(A*N+B)/M,Xm=Ym*M-B;
	if(Ym==0)return ans;
	ans+=(N-(Xm+A-1)/A)*Ym;
	ans+=floor_sum(Ym,A,M,(A-Xm%A)%A);
	return ans;
}
#line 4 "a.cpp"
int N,M;
int A[2000],B[2000];
main()
{
	cin>>N>>M;
	long ans=0;
	for(int i=0;i<N;i++)cin>>A[i];
	for(int i=0;i<M;i++)cin>>B[i];
	for(int i=0;i<N;i++)for(int j=0;j<M;j++)
	{
		ans+=2*floor_sum(B[j],B[j],A[i],A[i]);
		ans%=(int)1e9+7;
	}
	cout<<ans<<endl;
}