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

int main() {
    ll n,m;
    std::cin >> n>>m;
        const ll MOD = 1e9+7;

    vector<ll> a(n),b(m);

    for (int i = 0; i < n; i++) {
        std::cin >> a[i];
    }
    
    for (int i = 0; i < m; i++) {
        std::cin >> b[i];
    }
    ll ans = 0;
    for (int i = 0; i < m; i++) {
        for (int j = 0; j < n; j++) {
            ll g = gcd(a[j],b[i]);
            g%=MOD;
            ans += a[j]%MOD*(b[i]+1)%MOD - (b[i]-g+MOD)%MOD+MOD;
        }
        ans %= MOD;
    }
    std::cout << ans << std::endl;
}