;; SOLUTION
(defun super-digit (int-str)
  "Parse each char of INT-STR as int then sum and stringify, repeat until single char."
  (if (= (length int-str) 1)
      (parse-integer int-str)
      ;; tail
      (super-digit
       ;; int-str
       (prin1-to-string
        (apply '+
               (mapcar
                (lambda (x) (- (char-int x) 48)) ; 48 is char code of 0
                (coerce int-str 'list)))))))

;; this helps parsing stdin
(defun split-string (str delim)
  (let ((acc '())
        (beg 0))
    (loop while (let ((end (position delim str :start beg)))
                  (progn
                    (push (subseq str beg end) acc)
                    (if end
                        (setq beg (+ 1 end))
                        nil ; break while
                        ))))
    (nreverse acc)))

;; MAIN
(let* ((pair-n-k (split-string (read-line) #\Space))
       (n (car pair-n-k))
       (k (parse-integer (cadr pair-n-k))))
  (write (super-digit (prin1-to-string (* k (super-digit n))))))