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 findAns s =
    let
        fun findAnsAux [] = "NA"
          | findAnsAux [_] = "NA"
          | findAnsAux [_, _] = "NA"
          | findAnsAux (#"O" :: #"O" :: #"O" :: _) = "East"
          | findAnsAux (#"X" :: #"X" :: #"X" :: _) = "West"
          | findAnsAux (_ :: tl) = findAnsAux tl
    in
        findAnsAux (String.explode s)
    end


val () =
    let
        val s = readStr ()

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