(defun main (&rest argv)
  (declare (ignorable argv))
  (let* ((n (read))
         (az "abcdefghijklmnopqrstuvwxyz")
         (i 0))
    (dotimes (a 26)
      (dotimes (b 26)
        (dotimes (c 26)
          (dotimes (d 26)
            (when (= i (1- n)) (return))
            (format t "a~c~c~c~ca~%"
              (char az a)
              (char az b)
              (char az c)
              (char az d))
            (incf i)))))
    (format t "an~%")))

(main)