import re


def area_type(s):
    """Validate the type of area argument.

    Args:
        s (str): The parsed argument.

    Returns:
        str: The input string if valid.

    Raises:
        ValueError: If `s` does not match the regex.

    """
    lat_regex = r"-?[0-9]{1,2}(\.[0-9][0-9]?)?"
    lon_regex = r"-?[0-9]{1,3}(\.[0-9][0-9]?)?"

    if not re.compile(lat_regex + "/" + lon_regex + "/" + lat_regex + "/" + lon_regex).match(s):
        raise ValueError('Area is not provided in "65/-20/30/20" format. Moreover not more than two digits after the'
                         'decimal point are allowed.')
    return s