(defun bitto10 (bit)
    (cond ((equal bit '0) 0)
          ((equal bit '1) 1)
          (t (+ (mod bit 10) (* 2 (bitto10 (/ (- bit (mod bit 10)) 10)))))))

; 1，0からなるアトムのxor
(defun myxor (a b)
    (cond ((and (equal a '0) (equal b '0)) '0)
          ((and (equal a '0) (equal b '1)) '1)
          ((and (equal a '1) (equal b '0)) '1)
          ((and (equal a '1) (equal b '1)) '0)))

;複数桁のxor
(defun mylogxor (a b)
    (cond ((and (equal a 0) (equal b 0)) 0)
          ((and (equal a 0) (equal b 1)) 1)
          ((and (equal a 1) (equal b 0)) 1)
          ((and (equal a 1) (equal b 1)) 0)
          (t (+ (mod (myxor (mod a 10) (mod b 10)) 10) (* 10 (mylogxor (/ (- a (mod a 10)) 10) (/ (- b (mod b 10)) 10)))))))

(defun solve (a b) (bitto10 (mylogxor a b)))
(princ (solve (read) (read)))