from typing import Counter


def count_yes_questions(group_answers: list[str]) -> int:
    """Count the number of unique questions that are answered yes to across
    all people in a group.
    """

    yes_counts: Counter = Counter()

    for individual_answers in group_answers:

        for answer in individual_answers:

            yes_counts[answer] += 1

    return len(yes_counts.keys())