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


fun findIndex x nil = ~1
  | findIndex x (h::tl) = 
    if x = h then 0
    else 1 + findIndex x tl


val () =
    let
        val s = readStr ()

        val index = findIndex #"?" (String.explode s)
        val ans = String.sub ("yukicoder", index)
    in
        print (Char.toString ans ^ "\n")
    end