import operator
import functools


def all_answering_yes(survey: list[str]) -> int:
    """
    Counts the number of A-Z questions where every person
    in the survey group answered yes.
    """
    set_intersect_op = operator.and_
    central_response = functools.reduce(set_intersect_op, (set(response) for response in survey))
    return len(central_response)