fun readStr () =
    let
        fun scan reader stream = SOME (StringCvt.splitl (not o Char.isSpace) reader (StringCvt.skipWS reader stream))
    in
        valOf (TextIO.scanStream scan TextIO.stdIn)
    end


val () =
    let
        val s = readStr ()
        val t = readStr ()

        val ans = List.hd
                      (List.filter
                           (fn x =>
                               x <> s andalso x <> t)
                           ["watermelon", "beachball", "shrinebell"])
    in
        print (ans ^ "\n")
    end