fun readLine () =
    valOf (TextIO.inputLine TextIO.stdIn)


fun isUshitapuniaki s =
    let
        fun isUshitapuniakiAux [] = true
          | isUshitapuniakiAux [h] =
            Char.isAlpha h
          | isUshitapuniakiAux (h1 :: h2 ::tl) =
            if Char.isAlpha h1 andalso Char.isSpace h2
            then isUshitapuniakiAux tl
            else false
    in
        isUshitapuniakiAux (String.explode (String.substring(s, 0, String.size s - 1)))
    end
                
                    
val () =
    let
        val s = readLine ()
        
        val ans =
            if isUshitapuniaki s then "Yes"
            else "No"
    in
        print (ans ^ "\n")
    end