#include <iostream>
#include <vector>
#include <algorithm>
#include <cmath>
#include <string>
#include <queue>
#include <stack>
#include <set>
#include <map>
#include <iomanip>
#include <utility>
#include <tuple>
#include <functional>
#include <bitset>
#include <cassert>
#include <complex>
#include <stdio.h>
#include <time.h>
#include <numeric>
#include <random>
#include <unordered_map>
#include <unordered_set>
#define all(a) a.begin(),a.end()
#define rep(i, n) for (ll i = 0; i < (n); i++)
#define pb push_back
#define debug(x) cerr << __LINE__ << ' ' << #x << ':' << x << '\n'
#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
typedef pair<ll, ll> P;
typedef complex<ld> com;
constexpr int inf = 1000000010;
constexpr ll INF = 1000000000000000010;
constexpr ld eps = 1e-12;
constexpr ld pi = 3.141592653589793238;
template<class T, class U> inline bool chmax(T &a, const U &b) { if (a < b) { a = b; return true; } return false; }
template<class T, class U> inline bool chmin(T &a, const U &b) { if (a > b) { a = b; return true; } return false; }

constexpr ll mod = 1000000007;

ll modinv(ll a) {
	a %= mod;
	if (a == 0) abort();
	ll b = mod, u = 1, v = 0;
	while (b) {
		ll t = a / b;
		a -= t * b; swap(a, b);
		u -= t * v; swap(u, v);
	}
	u %= mod;
	if (u < 0) u += mod;
	return u;
}

int main() {
	cin.tie(0);
	ios::sync_with_stdio(false);
	cout << fixed << setprecision(20);

	ll n, m;
	cin >> n >> m;
	vector<ll> a(n), b(m);
	rep(i, n) cin >> a[i];
	rep(i, m) cin >> b[i];
	ll ans = 0;
	rep(i, n) {
		rep(j, m) {
			ll g = gcd(a[i], b[j]);
			ll x = (b[j] - g) * b[j] % mod;
			if (x & 1) x += mod;
			x >>= 1;
			ll sum = (b[j] + 1) * b[j] / 2 % mod;
			sum *= a[i]; sum %= mod;
			sum -= x; if (sum < 0) sum += mod;
			sum *= modinv(b[j]); sum %= mod;
			ans += sum;
		}
	}
	cout << ans * 2 % mod << '\n';
}