(defun check (x y M)
  (let* ((a (first M))
         (b (second M))
         (c (third M))
         (d (fourth M)))
    (= (+ (* a x) (* b y))
       (+ (* c x) (* d y)))))

(defun main (&rest argv)
  (declare (ignorable argv))
  (let* ((x (read))
         (y (read))
         (E '(1 0 0 1))
         (A '(0 1 1 0))
         (B '(1 1 1 -1))
         (A*B '(1 -1 1 1))
         (B*A '(1 1 -1 1))
         (A*B*A '(-1 1 1 1))
         (B*A*B '(2 0 0 -2))
         (A*B*A*B '(0 -2 2 0)))
    (format t "~d~%" (cond ((check x y E)
                             0)
                           ((or (check x y A)
                                (check x y B))
                             1)
                           ((or (check x y A*B)
                                (check x y B*A))
                             2)
                           ((or (check x y A*B*A)
                                (check x y B*A*B))
                             3)
                           ((check x y A*B*A*B)
                             4)
                           (t
                             -1)))))

(main)