//#define _GLIBCXX_DEBUG
#include <bits/stdc++.h>
#define rep(i, n) for(int i=0; i<n; ++i)
#define all(v) v.begin(), v.end()
#define rall(v) v.rbegin(), v.rend()
using namespace std;
using ll = int64_t;
using ld = long double;
using P = pair<int, int>;
using vs = vector<string>;
using vi = vector<int>;
using vvi = vector<vi>;
template<class T> using PQ = priority_queue<T>;
template<class T> using PQG = priority_queue<T, vector<T>, greater<T> >;
const int INF = 0xccccccc;
const ll LINF = 0xcccccccccccccccLL;
template<typename T1, typename T2>
inline bool chmax(T1 &a, T2 b) {return a < b && (a = b, true);}
template<typename T1, typename T2>
inline bool chmin(T1 &a, T2 b) {return a > b && (a = b, true);}
template<typename T1, typename T2>
istream &operator>>(istream &is, pair<T1, T2> &p) { return is >> p.first >> p.second;}
template<typename T1, typename T2>
ostream &operator<<(ostream &os, const pair<T1, T2> &p) { return os << p.first << ' ' << p.second;}

struct barrett {
	unsigned int _m;
	uint64_t im;
	barrett(unsigned int m):_m(m), im(uint64_t(-1)/m + 1) {}
	unsigned int umod() const {return _m;}
	unsigned int mul(unsigned int a, unsigned int b) const {
		uint64_t z = a;
		z *= b;
		uint64_t x = uint64_t(((unsigned __int128)(z)*im) >> 64);
		unsigned int v = (unsigned int)(z-x*_m);
		if(_m <= v) v += _m;
		return v;
	}
};

constexpr int64_t safe_mod(int64_t x, int64_t m) {
	x %= m;
	if(x < 0) x += m;
	return x;
}

constexpr pair<int64_t, int64_t> inv_gcd(int64_t a, int64_t b) {
	a = safe_mod(a, b);
	if(a == 0) return {b, 0};
	int64_t s = b, t = a;
	int64_t m0 = 0, m1 = 1;
	while(t) {
		int64_t u = s/t;
		s -= t*u;
		m0 -= m1*u;
		int64_t tmp = s;
		s = t;
		t = tmp;
		tmp = m0;
		m0 = m1;
		m1 = tmp;
	}
	if(m0 < 0) m0 += b/s;
	return {s, m0};
}

int64_t pow_mod(int64_t x, int64_t n, int m) {
	if(m == 1) return 0;
	barrett bt((unsigned int)(m));
	unsigned int r = 1, y = (unsigned int)(safe_mod(x, m));
	while(n) {
		if(n&1) r = bt.mul(r, y);
		y = bt.mul(y, y);
		n >>= 1;
	}
	return r;
}

int64_t inv_mod(int64_t x, int64_t m) {
	pair<int64_t, int64_t> z = inv_gcd(x, m);
	assert(z.first == 1);
	return z.second;
}

//(y, z) answer mod z = y, 無理な時は(-1, -1)
pair<int64_t, int64_t> crt(const vector<int64_t> &r, const vector<int64_t> &m) {
	int n = int(r.size());
	int64_t r0 = 0, m0 = 1;
	for(int i = 0; i < n; i++) {
		assert(1 <= m[i]);
		int64_t r1 = safe_mod(r[i], m[i]), m1 = m[i];
		if(m0 < m1) {
			swap(r0, r1);
			swap(m0, m1);
		}
		if(m0 % m1 == 0) {
			if(r0 % m1 != r1) return {-1, -1};
			continue;
		}
		int64_t g, im;
		tie(g, im) = inv_gcd(m0, m1);
		int64_t u1 = (m1/g);
		if((r1-r0)%g) return {-1, -1};
		int64_t x = (r1-r0)/g%u1 * im % u1;
		r0 += x*m0;
		m0 *= u1;
		if(r0 < 0) r0 += m0;
	}
	return {r0, m0};
}

//[0, n) (a*i+b)/m
int64_t floor_sum(int64_t n, int64_t m, int64_t a, int64_t b) {
	int64_t ans = 0;
	if(a >= m) {
		ans += ((n-1)*n>>1)*(a/m);
		a %= m;
	}
	if(b >= m) {
		ans += n*(b/m);
		b %= m;
	}
	int64_t y_max = (a*n+b)/m, x_max = y_max*m-b;
	if(y_max == 0) return ans;
	ans += (n - (x_max+a-1)/a) * y_max;
	ans += floor_sum(y_max, a, m, (a - x_max%a)%a);
	return ans;
}

const unsigned int mod = 1000000007;
//const unsigned int mod = 998244353;

struct mint {
	unsigned int x;
	mint():x(0) {}
	mint(int64_t x_) {
		int64_t v = int64_t(x_ % mod);
		if(v < 0) v += mod;
		x = (unsigned int)v;
	}
	static mint row(int v) {
		mint v_;
		v_.x = v;
		return v_;
	}
	mint operator-() const { return mint(-x);}
	mint& operator+=(const mint a) {
		if ((x += a.x) >= mod) x -= mod;
		return *this;
	}
	mint& operator-=(const mint a) {
		if ((x += mod-a.x) >= mod) x -= mod;
		return *this;
	}
	mint& operator*=(const mint a) {
		uint64_t z = x;
		z *= a.x;
		x = (unsigned int)(z % mod);
		return *this;
	}
	mint operator+(const mint a) const { return mint(*this) += a;}
	mint operator-(const mint a) const { return mint(*this) -= a;}
	mint operator*(const mint a) const { return mint(*this) *= a;}
	friend bool operator==(const mint &a, const mint &b) {return a.x == b.x;}
	friend bool operator!=(const mint &a, const mint &b) {return a.x != b.x;}
	mint &operator++() {
		x++;
		if(x == mod) x = 0;
		return *this;
	}
	mint &operator--() {
		if(x == 0) x = mod;
		x--;
		return *this;
	}
	mint operator++(int) {
		mint result = *this;
		++*this;
		return result;
	}
	mint operator--(int) {
		mint result = *this;
		--*this;
		return result;
	}
	mint pow(int64_t t) const {
		mint x_ = *this, r = 1;
		while(t) {
			if(t&1) r *= x_;
			x_ *= x_;
			t >>= 1;
		}
		return r;
	}
	//for prime mod
	mint inv() const { return pow(mod-2);}
	mint& operator/=(const mint a) { return *this *= a.inv();}
	mint operator/(const mint a) {return mint(*this) /= a;}
};

istream& operator>>(istream& is, mint& a) { return is >> a.x;}
ostream& operator<<(ostream& os, const mint& a) { return os << a.x;}

#define N 2010

//head

int n, m;
int a[N], b[N];
mint ans;

int main() {
	scanf("%d%d", &n, &m);
	rep(i, n) scanf("%d", a+i);
	rep(i, m) scanf("%d", b+i);
	rep(i, n) rep(j, m) {
		ans += floor_sum(b[j]+1, b[j], a[i], 0)<<1;
	}
	cout << ans << endl;
}