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 makeTable s =
    let
        val table = Array.array (10, 0)
    in
        (
          List.app (fn x =>
                       let
                           val index = Char.ord x - Char.ord #"0"
                           val oldValue = Array.sub (table, index)
                       in
                           Array.update (table, index, oldValue + 1)
                       end)
                   (String.explode s);
          table
        )
    end


fun findAns table =
    let
        fun findAnsAux 0 = List.tabulate (Array.sub (table, 0), (fn _ => #"0"))
          | findAnsAux n =
            List.tabulate (Array.sub (table, n), (fn _ => Char.chr (n + Char.ord #"0"))) @ findAnsAux (n - 1)
    in
        String.implode (findAnsAux 9)
    end


val () =
    let
        val n = readStr ()

        val table = makeTable n
        val ans = findAns table
    in
        print (ans ^ "\n")
    end