#pragma GCC optimize ("O2")
#pragma GCC target ("avx2")
#include<bits/stdc++.h>

using namespace std;
typedef long long ll;
#define rep(i, n) for(int i = 0; i < (n); i++)
#define rep1(i, n) for(int i = 1; i <= (n); i++)
#define co(x) cout << (x) << "\n"
#define cosp(x) cout << (x) << " "
#define ce(x) cerr << (x) << "\n"
#define cesp(x) cerr << (x) << " "
#define pb push_back
#define mp make_pair
#define chmin(x, y) x = min(x, y)
#define chmax(x, y) x = max(x, y)
#define Would
#define you
#define please

const int mod = 1000000007;
const int IMAX = 100000;
constexpr ll modpow(ll A, ll B) {
	ll kotae = 1;
	while (B > 0) {
		if (B & 1) kotae = kotae * A % mod;
		A = A * A % mod;
		B >>= 1;
	}
	return kotae;
}


int main() {
	cin.tie(0);
	ios::sync_with_stdio(false);


	int N, M;
	cin >> N >> M;
	ll A[2000], B[2000];
	rep(i, N) cin >> A[i];
	rep(i, M) cin >> B[i];


	ll kotae = 0;
	rep(j, M) rep(i, N) {
		ll tmp = A[i] * (B[j] * (B[j] + 1) / 2 % mod) % mod;
		ll are = __gcd(A[i], B[j]);
		ll kazu = B[j] / are;
		ll tmp2 = kazu * (kazu - 1) / 2 % mod * are % mod * are % mod;
		tmp = (tmp - tmp2 + mod) % mod;
		tmp = tmp * modpow(B[j], mod - 2) % mod;
		kotae += tmp;
	}
	co(kotae * 2 % mod);





	Would you please return 0;
}