def get_last_id(list_of_id, width):
    """ Gets the last identifier given a list of identifier.

    :param list_of_id: list of identifier
    :param width: the width of the identifier.
    :return: the last identifier.

    """
    last_number = 0
    for identifier in list_of_id:
        if identifier == "":
            last_number = 0
        else:
            last_number = max(last_number, int(identifier.lstrip('0')))
    last = (width - len(str(last_number))) * "0" + str(last_number)
    return last