#define MOD_TYPE 1

#pragma region Macros

#include <bits/stdc++.h>
using namespace std;

#if 0
#include <boost/multiprecision/cpp_int.hpp>
#include <boost/multiprecision/cpp_dec_float.hpp>
using Int = boost::multiprecision::cpp_int;
using lld = boost::multiprecision::cpp_dec_float_100;
#endif
#if 1
#pragma GCC target("avx2")
#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")
#endif
using ll = long long int;
using ld = long double;
using pii = pair<int, int>;
using pll = pair<ll, ll>;
using pld = pair<ld, ld>;
template <typename Q_type>
using smaller_queue = priority_queue<Q_type, vector<Q_type>, greater<Q_type>>;

constexpr ll MOD = (MOD_TYPE == 1 ? (ll)(1e9 + 7) : 998244353);
constexpr int INF = (int)1e9 + 10;
constexpr ll LINF = (ll)4e18;
constexpr double PI = acos(-1.0);
constexpr double EPS = 1e-7;
constexpr int Dx[] = {0, 0, -1, 1, -1, 1, -1, 1, 0};
constexpr int Dy[] = {1, -1, 0, 0, -1, -1, 1, 1, 0};

#define REP(i, m, n) for (ll i = m; i < (ll)(n); ++i)
#define rep(i, n) REP(i, 0, n)
#define REPI(i, m, n) for (int i = m; i < (int)(n); ++i)
#define repi(i, n) REPI(i, 0, n)
#define MP make_pair
#define MT make_tuple
#define YES(n) cout << ((n) ? "YES" : "NO") << "\n"
#define Yes(n) cout << ((n) ? "Yes" : "No") << "\n"
#define possible(n) cout << ((n) ? "possible" : "impossible") << "\n"
#define Possible(n) cout << ((n) ? "Possible" : "Impossible") << "\n"
#define all(v) v.begin(), v.end()
#define NP(v) next_permutation(all(v))
#define dbg(x) cerr << #x << ":" << x << "\n";

struct io_init
{
  io_init()
  {
    cin.tie(0);
    ios::sync_with_stdio(false);
    cout << setprecision(30) << setiosflags(ios::fixed);
  };
} io_init;
template <typename T>
inline bool chmin(T &a, T b)
{
  if (a > b)
  {
    a = b;
    return true;
  }
  return false;
}
template <typename T>
inline bool chmax(T &a, T b)
{
  if (a < b)
  {
    a = b;
    return true;
  }
  return false;
}
inline ll CEIL(ll a, ll b)
{
  return (a + b - 1) / b;
}
template <typename A, size_t N, typename T>
inline void Fill(A (&array)[N], const T &val)
{
  fill((T *)array, (T *)(array + N), val);
}
template <typename T, typename U>
constexpr istream &operator>>(istream &is, pair<T, U> &p) noexcept
{
  is >> p.first >> p.second;
  return is;
}
template <typename T, typename U>
constexpr ostream &operator<<(ostream &os, pair<T, U> &p) noexcept
{
  os << p.first << " " << p.second;
  return os;
}
#pragma endregion

#pragma region mint
template <int MOD>
struct Fp
{
  long long val;

  constexpr Fp(long long v = 0) noexcept : val(v % MOD)
  {
    if (val < 0)
      v += MOD;
  }

  constexpr int getmod()
  {
    return MOD;
  }

  constexpr Fp operator-() const noexcept
  {
    return val ? MOD - val : 0;
  }

  constexpr Fp operator+(const Fp &r) const noexcept
  {
    return Fp(*this) += r;
  }

  constexpr Fp operator-(const Fp &r) const noexcept
  {
    return Fp(*this) -= r;
  }

  constexpr Fp operator*(const Fp &r) const noexcept
  {
    return Fp(*this) *= r;
  }

  constexpr Fp operator/(const Fp &r) const noexcept
  {
    return Fp(*this) /= r;
  }

  constexpr Fp &operator+=(const Fp &r) noexcept
  {
    val += r.val;
    if (val >= MOD)
      val -= MOD;
    return *this;
  }

  constexpr Fp &operator-=(const Fp &r) noexcept
  {
    val -= r.val;
    if (val < 0)
      val += MOD;
    return *this;
  }

  constexpr Fp &operator*=(const Fp &r) noexcept
  {
    val = val * r.val % MOD;
    if (val < 0)
      val += MOD;
    return *this;
  }

  constexpr Fp &operator/=(const Fp &r) noexcept
  {
    long long a = r.val, b = MOD, u = 1, v = 0;
    while (b)
    {
      long long t = a / b;
      a -= t * b;
      swap(a, b);
      u -= t * v;
      swap(u, v);
    }
    val = val * u % MOD;
    if (val < 0)
      val += MOD;
    return *this;
  }

  constexpr bool operator==(const Fp &r) const noexcept
  {
    return this->val == r.val;
  }

  constexpr bool operator!=(const Fp &r) const noexcept
  {
    return this->val != r.val;
  }

  friend constexpr ostream &operator<<(ostream &os, const Fp<MOD> &x) noexcept
  {
    return os << x.val;
  }

  friend constexpr istream &operator>>(istream &is, Fp<MOD> &x) noexcept
  {
    return is >> x.val;
  }
};

Fp<MOD> modpow(const Fp<MOD> &a, long long n) noexcept
{
  if (n == 0)
    return 1;
  auto t = modpow(a, n / 2);
  t = t * t;
  if (n & 1)
    t = t * a;
  return t;
}

using mint = Fp<MOD>;
#pragma endregion

namespace atcoder
{

  namespace internal
  {

    // @param m `1 <= m`
    // @return x mod m
    constexpr long long safe_mod(long long x, long long m)
    {
      x %= m;
      if (x < 0)
        x += m;
      return x;
    }

    // Fast modular multiplication by barrett reduction
    // Reference: https://en.wikipedia.org/wiki/Barrett_reduction
    // NOTE: reconsider after Ice Lake
    struct barrett
    {
      unsigned int _m;
      unsigned long long im;

      // @param m `1 <= m < 2^31`
      barrett(unsigned int m) : _m(m), im((unsigned long long)(-1) / m + 1) {}

      // @return m
      unsigned int umod() const { return _m; }

      // @param a `0 <= a < m`
      // @param b `0 <= b < m`
      // @return `a * b % m`
      unsigned int mul(unsigned int a, unsigned int b) const
      {
        // [1] m = 1
        // a = b = im = 0, so okay

        // [2] m >= 2
        // im = ceil(2^64 / m)
        // -> im * m = 2^64 + r (0 <= r < m)
        // let z = a*b = c*m + d (0 <= c, d < m)
        // a*b * im = (c*m + d) * im = c*(im*m) + d*im = c*2^64 + c*r + d*im
        // c*r + d*im < m * m + m * im < m * m + 2^64 + m <= 2^64 + m * (m + 1) < 2^64 * 2
        // ((ab * im) >> 64) == c or c + 1
        unsigned long long z = a;
        z *= b;
#ifdef _MSC_VER
        unsigned long long x;
        _umul128(z, im, &x);
#else
        unsigned long long x =
            (unsigned long long)(((unsigned __int128)(z)*im) >> 64);
#endif
        unsigned int v = (unsigned int)(z - x * _m);
        if (_m <= v)
          v += _m;
        return v;
      }
    };

    // @param n `0 <= n`
    // @param m `1 <= m`
    // @return `(x ** n) % m`
    constexpr long long pow_mod_constexpr(long long x, long long n, int m)
    {
      if (m == 1)
        return 0;
      unsigned int _m = (unsigned int)(m);
      unsigned long long r = 1;
      unsigned long long y = safe_mod(x, m);
      while (n)
      {
        if (n & 1)
          r = (r * y) % _m;
        y = (y * y) % _m;
        n >>= 1;
      }
      return r;
    }

    // Reference:
    // M. Forisek and J. Jancina,
    // Fast Primality Testing for Integers That Fit into a Machine Word
    // @param n `0 <= n`
    constexpr bool is_prime_constexpr(int n)
    {
      if (n <= 1)
        return false;
      if (n == 2 || n == 7 || n == 61)
        return true;
      if (n % 2 == 0)
        return false;
      long long d = n - 1;
      while (d % 2 == 0)
        d /= 2;
      constexpr long long bases[3] = {2, 7, 61};
      for (long long a : bases)
      {
        long long t = d;
        long long y = pow_mod_constexpr(a, t, n);
        while (t != n - 1 && y != 1 && y != n - 1)
        {
          y = y * y % n;
          t <<= 1;
        }
        if (y != n - 1 && t % 2 == 0)
        {
          return false;
        }
      }
      return true;
    }
    template <int n>
    constexpr bool is_prime = is_prime_constexpr(n);

    // @param b `1 <= b`
    // @return pair(g, x) s.t. g = gcd(a, b), xa = g (mod b), 0 <= x < b/g
    constexpr std::pair<long long, long long> inv_gcd(long long a, long long b)
    {
      a = safe_mod(a, b);
      if (a == 0)
        return {b, 0};

      // Contracts:
      // [1] s - m0 * a = 0 (mod b)
      // [2] t - m1 * a = 0 (mod b)
      // [3] s * |m1| + t * |m0| <= b
      long long s = b, t = a;
      long long m0 = 0, m1 = 1;

      while (t)
      {
        long long u = s / t;
        s -= t * u;
        m0 -= m1 * u; // |m1 * u| <= |m1| * s <= b

        // [3]:
        // (s - t * u) * |m1| + t * |m0 - m1 * u|
        // <= s * |m1| - t * u * |m1| + t * (|m0| + |m1| * u)
        // = s * |m1| + t * |m0| <= b

        auto tmp = s;
        s = t;
        t = tmp;
        tmp = m0;
        m0 = m1;
        m1 = tmp;
      }
      // by [3]: |m0| <= b/g
      // by g != b: |m0| < b/g
      if (m0 < 0)
        m0 += b / s;
      return {s, m0};
    }

    // Compile time primitive root
    // @param m must be prime
    // @return primitive root (and minimum in now)
    constexpr int primitive_root_constexpr(int m)
    {
      if (m == 2)
        return 1;
      if (m == 167772161)
        return 3;
      if (m == 469762049)
        return 3;
      if (m == 754974721)
        return 11;
      if (m == 998244353)
        return 3;
      int divs[20] = {};
      divs[0] = 2;
      int cnt = 1;
      int x = (m - 1) / 2;
      while (x % 2 == 0)
        x /= 2;
      for (int i = 3; (long long)(i)*i <= x; i += 2)
      {
        if (x % i == 0)
        {
          divs[cnt++] = i;
          while (x % i == 0)
          {
            x /= i;
          }
        }
      }
      if (x > 1)
      {
        divs[cnt++] = x;
      }
      for (int g = 2;; g++)
      {
        bool ok = true;
        for (int i = 0; i < cnt; i++)
        {
          if (pow_mod_constexpr(g, (m - 1) / divs[i], m) == 1)
          {
            ok = false;
            break;
          }
        }
        if (ok)
          return g;
      }
    }
    template <int m>
    constexpr int primitive_root = primitive_root_constexpr(m);

  } // namespace internal

} // namespace atcoder

namespace atcoder
{

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

  long long inv_mod(long long x, long long m)
  {
    assert(1 <= m);
    auto z = internal::inv_gcd(x, m);
    assert(z.first == 1);
    return z.second;
  }

  // (rem, mod)
  std::pair<long long, long long> crt(const std::vector<long long> &r,
                                      const std::vector<long long> &m)
  {
    assert(r.size() == m.size());
    int n = int(r.size());
    // Contracts: 0 <= r0 < m0
    long long r0 = 0, m0 = 1;
    for (int i = 0; i < n; i++)
    {
      assert(1 <= m[i]);
      long long r1 = internal::safe_mod(r[i], m[i]), m1 = m[i];
      if (m0 < m1)
      {
        std::swap(r0, r1);
        std::swap(m0, m1);
      }
      if (m0 % m1 == 0)
      {
        if (r0 % m1 != r1)
          return {0, 0};
        continue;
      }
      // assume: m0 > m1, lcm(m0, m1) >= 2 * max(m0, m1)

      // (r0, m0), (r1, m1) -> (r2, m2 = lcm(m0, m1));
      // r2 % m0 = r0
      // r2 % m1 = r1
      // -> (r0 + x*m0) % m1 = r1
      // -> x*u0*g % (u1*g) = (r1 - r0) (u0*g = m0, u1*g = m1)
      // -> x = (r1 - r0) / g * inv(u0) (mod u1)

      // im = inv(u0) (mod u1) (0 <= im < u1)
      long long g, im;
      std::tie(g, im) = internal::inv_gcd(m0, m1);

      long long u1 = (m1 / g);
      // |r1 - r0| < (m0 + m1) <= lcm(m0, m1)
      if ((r1 - r0) % g)
        return {0, 0};

      // u1 * u1 <= m1 * m1 / g / g <= m0 * m1 / g = lcm(m0, m1)
      long long x = (r1 - r0) / g % u1 * im % u1;

      // |r0| + |m0 * x|
      // < m0 + m0 * (u1 - 1)
      // = m0 + m0 * m1 / g - m0
      // = lcm(m0, m1)
      r0 += x * m0;
      m0 *= u1; // -> lcm(m0, m1)
      if (r0 < 0)
        r0 += m0;
    }
    return {r0, m0};
  }

  long long floor_sum(long long n, long long m, long long a, long long b)
  {
    long long ans = 0;
    if (a >= m)
    {
      ans += (n - 1) * n * (a / m) / 2;
      a %= m;
    }
    if (b >= m)
    {
      ans += n * (b / m);
      b %= m;
    }

    long long 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;
  }

} // namespace atcoder

void solve()
{
  int n, m;
  cin >> n >> m;
  vector<ll> a(n), b(m);
  rep(i, n) cin >> a[i];
  rep(i, m) cin >> b[i];
  mint ans = 0;
  rep(i, n) rep(j, m)
  {
    ans += atcoder::floor_sum(b[j] + 1, b[j], a[i], 0) * 2;
  }
  cout << ans << "\n";
}

int main()
{
  solve();
}