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



val () =
    let
        val a = Word.fromInt(readInt ())
        val b = Word.fromInt(readInt ())

        val ans = Word.toInt(Word.orb(a, b)) - Word.toInt(Word.andb(a, b))
    in
        print (Int.toString ans ^ "\n")
    end