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
        val n = readStr ()

        val numOfZero =
            List.foldl
                (fn (ch, acc) =>
                    if ch = #"0" then 1 + acc
                    else acc)
                0
                (String.explode n)
        val ans = Int.abs (8 - numOfZero)
    in
        print (Int.toString ans ^ "\n")  
    end