(defun main (&rest argv)
  (declare (ignorable argv))
  (let* ((a (read))
         (b (read)))
    (format t "~d~%" (cond ((< a b)
                             (- b 2))
                           ((> a b)
                             (- 2000000000 b 1))
                           (t
                             0)))))

(main)