from math import ceil


def floor_sum_of_linear(L: int, R: int, a: int, b: int, mod: int) -> int:
    """
    ```
    sum((x * a + b) // mod for x in range(L, R))
    ```
    """
    if L >= R:
        return 0
    res = 0
    b += L * a
    n = R - L

    if b < 0:
        k = ceil(-b / mod)
        b += k * mod
        res -= n * k

    while n:
        q, a = a // mod, a % mod
        res += n * (n - 1) // 2 * q
        if b >= mod:
            q, b = b // mod, b % mod
            res += n * q
        n, b = (a * n + b) // mod, (a * n + b) % mod
        a, mod = mod, a

    return res


if __name__ == "__main__":
    import sys

    sys.setrecursionlimit(int(1e9))
    input = lambda: sys.stdin.readline().rstrip("\r\n")

    N = int(input())
    M = int(input())
    A = list(map(int, input().split()))
    B = list(map(int, input().split()))
    ans = 0
    for a in A:
        for b in B:
            ans += floor_sum_of_linear(1, b + 1, a, 0, b)
    ans *= 2
    ans %= int(1e9 + 7)
    print(ans)