#include <bits/stdc++.h>
using namespace std;
const long long MOD = 1000000007;
//https://judge.yosupo.jp/submission/7028
long long gauss_sum(long long n, long long a, long long b, long long c) {
	if (n == 0) return 0;
	long long res = 0;
	{
		long long p = a / c;
		res += n * (n-1) / 2 * p;
		a %= c;
	}
	{
		long long p = b / c;
		res += n * p;
		b %= c;
	}
	if (a == 0) return res;
	long long top = (a * (n-1) + b) / c;
	res += top * n;
	long long h = 1;
	if (h <= top) {
		res -= gauss_sum(top - h + 1, c, c * h - (b + 1), a) + top - h + 1;
	}
	return res;
}
int main(){
  int N;
  cin >> N;
  int M;
  cin >> M;
  vector<long long> A(N);
  for (int i = 0; i < N; i++){
    cin >> A[i];
  }
  vector<long long> B(M);
  for (int i = 0; i < M; i++){
    cin >> B[i];
  }
  long long ans = 0;
  for (int i = 0; i < N; i++){
    for (int j = 0; j < M; j++){
      long long tmp = gauss_sum(B[j], A[i], A[i], B[j]);
      ans += tmp % MOD;
    }
  }
  ans *= 2;
  ans %= MOD;
  cout << ans << endl;
}