#include <bits/stdc++.h>
using namespace std;
using ll = long long;

const ll mod = 1000000007;
const int INF = 1001001001;

ll gcd(ll a, ll b){return (b == 0 ? a : gcd(b, a % b));}
ll lcm(ll a, ll b){return a / gcd(a, b) * b;}

void solve() {
    int n, m;
    std::cin >> n >> m;

    std::vector<ll> xs(n), ys(m);
    for (auto& x : xs) std::cin >> x;
    for (auto& y : ys) std::cin >> y;

    ll ans = 0;
    for (ll a : xs) {
        for (ll b : ys) {
            ans += a * b % mod + a - b + gcd(a, b);
            ans %= mod;
        }
    }

    std::cout << ans << "\n";
}
int main(){
    solve();
}