(define (f n)
  (let
    ((grundy (make-vector 101 0)))
    (vector-set! grundy 2 1)
    (do
      ((i 3 (+ i 1)))
      ((> i n))
      (let*
        ((a (bitwise-xor (vector-ref grundy (quotient i 3)) (vector-ref grundy (+ (quotient i 3) (if (> (remainder i 3) 0) 1 0))) (vector-ref grundy (+ (quotient i 3) (if (> (remainder i 3) 1) 1 0))))))
        ((b (bitwise-xor (vector-ref grundy (quotient i 2)) (vector-ref grundy (+ (quotient i 2) (if (= (remainder i 2) 1) 1 0))))))
        (let loop ()
          (when (or (= (vector-ref grundy i) a) (= (vector-ref grundy i) b))
            (vector-set! grundy i (+ 1 (vector-ref grundy i)))
            (loop)))))
    grundy))

(define yuki153
  (let* ((n (read)) (grundy (f n)))
    (if (= n 1)
      (display "B\n")
      (if (zero? (vector-ref grundy n))
        (display "B\n")
        (display "A\n")))))