#include <cmath>
#include <vector>
#include <iostream>
#include <algorithm>
#include <set>
#include <iomanip>
#include <numeric>
#include <queue>
#include <string>
#include <map>
#include <fstream>
#include <cassert>
#include <stack>
#include <climits>
long long int gcd(const long long int a, const long long int b) {
	return b == 0 ? a : gcd(b, a % b);
}
int main() {
	std::cin.tie(nullptr); std::cin.sync_with_stdio(false);
	int n, m; std::cin >> n >> m;
	std::vector<long long int> a_num(n), b_num(m);
	for (auto& a : a_num) std::cin >> a;
	for (auto& b : b_num) std::cin >> b;
	constexpr long long int MOD = 1000000007;
	long long int result{ 0 };
	for (const auto a : a_num) {
		for (const auto b : b_num) {
			const auto g = gcd(a, b);
			const auto bd = b / g;
			result = (result + ((b + 1) * a % MOD - (bd - 1) * g % MOD)) % MOD;
		}
	}
	std::cout << (result + MOD) % MOD << '\n';
}