(use util.match)

(define (main args)
  (print
   (let1 ls (string->list (read-line))
         (let loop ([ls ls])
           (match ls
                  [(a b . c) (if (and (char-lower-case? a) (char=? b #\space))
                                 (loop c)
                                 "No")]
                  [(a) (if (char-lower-case? a) "Yes" "No")]
                  [() "Yes"]))))
  0)