import re


def get_offer_total_floors(html_parser, default_value=''):
    """
    This method returns the maximal number of floors in the building.

    :param html_parser: a BeautifulSoup object
    :rtype: string
    :return: The maximal floor number
    """
    # searching dom for floor data
    floor_raw_data = html_parser.find(class_="param_floor_no")
    if hasattr(floor_raw_data, 'span'):
        floor_data = floor_raw_data.span.text
    else:
        return default_value
    # extracting information about floor
    match = re.search(r"\w+\s(?P<total>\d+)", floor_data)
    total_floors = default_value
    if match:
        total_floors = match.groupdict().get("total")
    return total_floors