def part_a(data) -> int:
    """
    Solution for part a

    Parameters
    ----------
    data: str

    Returns
    -------
    answer: int

    """
    groups = data.split('\n\n')
    as_one = (group.replace('\n', '') for group in groups)
    unique = (set(group) for group in as_one)
    return sum(len(group) for group in unique)