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


val () =
    let
        val x = readInt ()
        val y = readInt ()
        val r = readInt ()

        val ans = abs x + abs y + Real.ceil (Math.sqrt 2.0 * (Real.fromInt r) )
    in
        print (Int.toString ans ^ "\n")
    end