#include <cassert>
#include <cmath>
#include <cstdint>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <algorithm>
#include <bitset>
#include <complex>
#include <deque>
#include <functional>
#include <iostream>
#include <map>
#include <numeric>
#include <queue>
#include <set>
#include <sstream>
#include <string>
#include <unordered_map>
#include <unordered_set>
#include <utility>
#include <vector>

using namespace std;

using Int = long long;

template <class T1, class T2> ostream &operator<<(ostream &os, const pair<T1, T2> &a) { return os << "(" << a.first << ", " << a.second << ")"; };
template <class T> void pv(T a, T b) { for (T i = a; i != b; ++i) cerr << *i << " "; cerr << endl; }
template <class T> bool chmin(T &t, const T &f) { if (t > f) { t = f; return true; } return false; }
template <class T> bool chmax(T &t, const T &f) { if (t < f) { t = f; return true; } return false; }


template<int M_> struct ModInt {
  static constexpr int M = M_;
  int x;
  constexpr ModInt() : x(0) {}
  constexpr ModInt(long long x_) : x(x_ % M) { if (x < 0) x += M; }
  ModInt &operator+=(const ModInt &a) { x += a.x; if (x >= M) x -= M; return *this; }
  ModInt &operator-=(const ModInt &a) { x -= a.x; if (x < 0) x += M; return *this; }
  ModInt &operator*=(const ModInt &a) { x = static_cast<int>((static_cast<long long>(x) * a.x) % M); return *this; }
  ModInt &operator/=(const ModInt &a) { return (*this *= a.inv()); }
  ModInt operator+(const ModInt &a) const { return (ModInt(*this) += a); }
  ModInt operator-(const ModInt &a) const { return (ModInt(*this) -= a); }
  ModInt operator*(const ModInt &a) const { return (ModInt(*this) *= a); }
  ModInt operator/(const ModInt &a) const { return (ModInt(*this) /= a); }
  ModInt operator-() const { return ModInt(-x); }
  ModInt pow(long long e) const {
    if (e < 0) return inv().pow(-e);
    ModInt x2 = x, xe = 1;
    for (; e; e >>= 1) {
      if (e & 1) xe *= x2;
      x2 *= x2;
    }
    return xe;
  }
  ModInt inv() const {
    int a = x, b = M, y = 1, z = 0, t;
    for (; ; ) {
      t = a / b; a -= t * b;
      if (a == 0) {
        assert(b == 1 || b == -1);
        return ModInt(b * z);
      }
      y -= t * z;
      t = b / a; b -= t * a;
      if (b == 0) {
        assert(a == 1 || a == -1);
        return ModInt(a * y);
      }
      z -= t * y;
    }
  }
  friend ModInt operator+(long long a, const ModInt &b) { return (ModInt(a) += b); }
  friend ModInt operator-(long long a, const ModInt &b) { return (ModInt(a) -= b); }
  friend ModInt operator*(long long a, const ModInt &b) { return (ModInt(a) *= b); }
  friend std::ostream &operator<<(std::ostream &os, const ModInt &a) { return os << a.x; }
};

constexpr int MO = 1000000007;
using Mint = ModInt<MO>;


// floor(a / b)
Int divFloor(Int a, Int b) {
  return a / b - (((a ^ b) < 0 && a % b != 0) ? 1 : 0);
}

// sum_{x=l}^r floor((a x + b) / m)
// m > 0
Mint sumFloors(Int m, Int a, Int b, Int l, Int r) {
  Mint sum;
  for (; l <= r; ) {
    const Int q = divFloor(a, m);
    const Int aa = a - q * m;
    const Int ll = divFloor(aa * l + b, m) + 1;
    const Int rr = divFloor(aa * r + b, m);
    sum += Mint(q) * Mint((r + 1) * r / 2 - l * (l - 1) / 2) + Mint(r) * Mint(rr) - Mint(l - 1) * Mint(ll - 1) + Mint(rr - ll + 1);
    a = m; m = aa; l = -rr; r = -ll;
  }
  return sum;
}


int M, N;
vector<Int> A, B;

int main() {
  for (; ~scanf("%d%d", &M, &N); ) {
    A.resize(M);
    for (int i = 0; i < M; ++i) {
      scanf("%lld", &A[i]);
    }
    B.resize(N);
    for (int j = 0; j < N; ++j) {
      scanf("%lld", &B[j]);
    }
    
    Mint ans = 0;
    for (int i = 0; i < M; ++i) for (int j = 0; j < N; ++j) {
      ans += sumFloors(B[j], A[i], 0, 1, B[j]);
    }
    ans *= 2;
    printf("%d\n", ans.x);
  }
  return 0;
}