def remove_subdomain(name: str) -> str:
    """Removes the subdomain from a given URL.

    Example:
        >>> remove_subdomain("www.example.com")
        '.example.com'

    Arguments:
        name: the domain

    Returns:
        the string with the subdomain removed. The string starts with the dot.
    """
    try:
        pos = name.index(".")
    except ValueError:
        return name
    return name[pos:]