from typing import Counter


def repeating_bits(n: list[str], index: int) -> tuple:
    """
    Find most and least repeating bit in given index
    :param n: list of numbers as strings
    :param index: index of bit to find
    :return: tuple of most and least repeating bit
    """
    bits = [int(i[index]) for i in n]
    c = Counter(bits)
    return c.most_common()[0][0], c.most_common()[-1][0]