(require 'asdf)

(asdf:load-system "cl-strings")

(require :cl-strings)

(defun diff (data)
  (let* ((lists (reduce (lambda (acc itm) (cons (cons (parse-integer (car itm)) (car acc)) (cons (parse-integer (cadr itm)) (cdr acc))))
                        (mapcar (lambda (line) (cl-strings:split line "   "))
                                (cl-strings:split data "
"))
                        :initial-value (cons (list) (list))))
         (sorted (cons (sort (copy-seq (car lists)) #'<)
                       (sort (copy-seq (cdr lists)) #'<))))
    (reduce #'+ (mapcar (lambda (itm1 itm2) (abs (- itm1 itm2)))
                        (car sorted)
                        (cdr sorted)))))

(format t "~s~%" (diff "3   4
4   3
2   5
1   3
3   9
3   3"))

(format t "~s~%" (diff (string-right-trim '(#\Space #\Newline) (uiop:read-file-string "input"))))