def solve_dumb(k,m,d):
    count = 0
    books_today = 1
    holiday_count = 0
    while True:
        m -= books_today
        books_today += 1
        if (d%7) == 0 or (d%7) == 6:
            pass
            holiday_count += 1
        else:
            m += k

        if m < 0:
            break
        else:
            d += 1
            count += 1

        # print(books_today-1, m, d)

    # print('holi', holiday_count)
    return count