// #pragma GCC optimize ("Ofast")
// #pragma GCC optimize ("unroll-loops")
// #pragma GCC target ("avx,avx2,fma")
#include <bits/stdc++.h>

#define for(i, a, b) for(int i = (a); i <= (b); i ++)
using std::cin, std::cout, std::cerr;
using ll = long long;

const ll P = 1e9 + 7;

int main() {
    std::ios::sync_with_stdio(false);
    int n, m; cin >> n >> m;
    std::vector<int> a(n), b(m);
    for(i, 0, n - 1) cin >> a[i];
    for(i, 0, m - 1) cin >> b[i];
    ll ans = 0;
    for(i, 0, n - 1) for(j, 0, m - 1) if(a[i]) {
        int g = std::__gcd(a[i], b[j]);
        ans += ll(a[i]) * (b[j] +1);
        ans -= b[j] - g;
        ans %= P;
    }
    ans = (ans % P + P) % P;
    cout << ans << '\n';
}