(defun main (&rest argv)
  (declare (ignorable argv))
  (let* ((s (read-line)))
    (format t "~a~%" (if (and (char= (aref s 0) (aref s 1))
                              (char/= (aref s 0) (aref s 2)))
                         "Yes"
                         "No"))))

(main)