import std.conv, std.functional, std.range, std.stdio, std.string;
import std.algorithm, std.array, std.bigint, std.bitmanip, std.complex, std.container, std.math, std.mathspecial, std.numeric, std.regex, std.typecons;
import core.bitop;

class EOFException : Throwable { this() { super("EOF"); } }
string[] tokens;
string readToken() { for (; tokens.empty; ) { if (stdin.eof) { throw new EOFException; } tokens = readln.split; } auto token = tokens.front; tokens.popFront; return token; }
int readInt() { return readToken.to!int; }
long readLong() { return readToken.to!long; }
real readReal() { return readToken.to!real; }

bool chmin(T)(ref T t, in T f) { if (t > f) { t = f; return true; } else { return false; } }
bool chmax(T)(ref T t, in T f) { if (t < f) { t = f; return true; } else { return false; } }

int binarySearch(alias pred, T)(in T[] as) { int lo = -1, hi = cast(int)(as.length); for (; lo + 1 < hi; ) { const mid = (lo + hi) >> 1; (unaryFun!pred(as[mid]) ? hi : lo) = mid; } return hi; }
int lowerBound(T)(in T[] as, T val) { return as.binarySearch!(a => (a >= val)); }
int upperBound(T)(in T[] as, T val) { return as.binarySearch!(a => (a > val)); }


struct ModInt(int M_) {
  import std.conv : to;
  alias M = M_;
  int x;
  this(ModInt a) { x = a.x; }
  this(long a) { x = cast(int)(a % M); if (x < 0) x += M; }
  ref ModInt opAssign(long a) { return (this = ModInt(a)); }
  ref ModInt opOpAssign(string op)(ModInt a) {
    static if (op == "+") { x += a.x; if (x >= M) x -= M; }
    else static if (op == "-") { x -= a.x; if (x < 0) x += M; }
    else static if (op == "*") { x = cast(int)((cast(long)(x) * a.x) % M); }
    else static if (op == "/") { this *= a.inv(); }
    else static assert(false);
    return this;
  }
  ref ModInt opOpAssign(string op)(long a) {
    static if (op == "^^") {
      if (a < 0) return (this = inv()^^(-a));
      ModInt t2 = this, te = ModInt(1);
      for (long e = a; e > 0; e >>= 1) {
        if (e & 1) te *= t2;
        t2 *= t2;
      }
      x = cast(int)(te.x);
      return this;
    } else return mixin("this " ~ op ~ "= ModInt(a)");
  }
  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;
    }
  }
  ModInt opUnary(string op: "-")() const { return ModInt(-x); }
  ModInt opBinary(string op, T)(T a) const {
    return mixin("ModInt(this) " ~ op ~ "= a");
  }
  ModInt opBinaryRight(string op)(long a) const {
    return mixin("ModInt(a) " ~ op ~ "= this");
  }
  bool opCast(T: bool)() const { return (x != 0); }
  string toString() const { return x.to!string; }
}

enum MO = 1000000007;
alias Mint = ModInt!MO;


// floor(a / b)
Int divFloor(Int)(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
/*
long sumFloors(long m, long a, long b, long l, long r)
in {
  assert(m > 0, "sumFloors: m > 0 must hold");
}
do {
  long sum;
  for (; l <= r; ) {
    const q = divFloor(a, m);
    const aa = a - q * m;
    const ll = divFloor(aa * l + b, m) + 1;
    const rr = divFloor(aa * r + b, m);
    sum += q * ((r + 1) * r / 2 - l * (l - 1) / 2) + r * rr - (l - 1) * (ll - 1) + (rr - ll + 1);
    a = m; m = aa; l = -rr; r = -ll;
  }
  return sum;
}
*/
Mint sumFloors(long m, long a, long b, long l, long r)
in {
  assert(m > 0, "sumFloors: m > 0 must hold");
}
do {
  Mint sum;
  for (; l <= r; ) {
    const q = divFloor(a, m);
    const aa = a - q * m;
    const ll = divFloor(aa * l + b, m) + 1;
    const 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;
}


void main() {
  try {
    for (; ; ) {
      const M = readInt();
      const N = readInt();
      auto A = new long[M];
      foreach (i; 0 .. M) {
        A[i] = readLong();
      }
      auto B = new long[N];
      foreach (j; 0 .. N) {
        B[j] = readLong();
      }
      
      Mint ans;
      foreach (i; 0 .. M) foreach (j; 0 .. N) {
        ans += sumFloors(B[j], A[i], 0, 1, B[j]);
      }
      ans *= 2;
      writeln(ans);
break;
    }
  } catch (EOFException e) {
  }
}