anchor.diff:        (loop :named l :for line := (read-line in nil nil) :while line
            :do (let ((dir (subseq line 0 1))
                      (step (or (parse-integer (subseq line 1) :junk-allowed t) 0)))
  -               ;; (format t "[~A ~A]" dir steps)
                  (if (and (find dir '("R" "L" "U" "D") :test #'string=) (check-prime step))
                      (progn 
                        (cond ((string= dir "R") (setf x (+ x step)))
  
positive.code:                      (setf steps (+ steps step))
                       (setf num-of-move (1+ num-of-move)))
                     (return-from l nil)))))
      ;; (print (cons x y))
      (if (equal *problem* (cons x y))
          (list num-of-move steps)
          nil)))
  
negative.code:     (setf *problem* (cons x y))))
  
  (defun start-timer ()
    (reset-srv)
    (set-problem)
    (format t "(min): ")
    (setf *starttime* (+ (* (read) 60 1000) (get-internal-real-time)))
  