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
        fun loop n =
            (
              print (StringCvt.padLeft #"0" 3 (Int.toString n) ^ "\n");
              let
                  val res = readStr ()
              in
                  if res = "locked" then loop (n + 1)
                  else ignore ()
              end
            )
    in
        loop 0
    end