fun readInt () =
    valOf (TextIO.scanStream (Int.scan StringCvt.DEC) TextIO.stdIn)


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


datatype state = Sleeping | Awake

fun findAns _ _ [] acc = List.rev acc
  | findAns index Sleeping (h :: tl) acc =
    if h = #"o"
    then findAns (index + 1) Awake tl (index :: acc)
    else findAns (index + 1) Sleeping tl acc
  | findAns index Awake (h :: tl) acc = 
    if h = #"o"
    then findAns (index + 1) Awake tl acc
    else findAns (index + 1) Sleeping tl acc


fun printList [] = print "\n"
  | printList [x] =
    (
      print (Int.toString x);
      printList []
    )
  | printList (h :: tl) = 
    (
      print (Int.toString h);
      print " ";
      printList tl
    )


val () =
    let
        val n = readInt ()
        val s = readStr ()

        val ans = findAns 1 Sleeping (String.explode s) []
    in
        (
          print (Int.toString (List.length ans) ^ "\n");
          printList ans
        )
    end