def compute_FLOP(nl, nL, sl, ml):
    """
    compute the flop of the model (operation complex)
    :param nl: channel(filter) num of the input
    :param nL: filter num
    :param sl: kernel size
    :param ml: output spacial size(length)
    :return: the flop estimation
    """
    return nl * nL * sl * sl * ml * ml