def akm(m: int, n: int) -> int:
    """
    Ackmann 函数
    Args:
        m (int):m >= 0
        n (int):n >= 0
    Returns: int
    """
    assert m >= 0 and n >= 0, 'm, n must greater than 0'
    if m == 0:
        return n + 1
    elif n == 0:
        return akm(m - 1, 1)
    else:
        # n > 0
        return akm(m - 1, akm(m, n - 1))