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

fun findAns 0 0 _ = 0
  | findAns 0 y l = if 0 < y then (y + l - 1) div l
                    else ((abs y + l - 1) div l) + 2
  | findAns x 0 l = ((abs x + l - 1) div l) + 1
  | findAns x y l = if 0 < x andalso 0 < y then ((y + l - 1) div l) + ((x + l - 1) div l) + 1
                    else if 0 < x andalso y < 0 then ((x + l - 1) div l) + 1 + ((abs y + l - 1) div l) + 1
                    else if x < 0 andalso 0 < y then ((y + l - 1) div l) + ((abs x + l - 1) div l) + 1
                    else (* x < 0 andalso y < 0 *) ((abs x + l - 1) div l) + 1 + ((abs y + l - 1) div l) + 1

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

        val ans = findAns x y l
    in
        print (Int.toString ans)
    end