open System
type Sol() =
    member this.Solve() = 
        let X = stdin.ReadLine() |> int
        let Y = stdin.ReadLine() |> int
        let L = stdin.ReadLine() |> int
        
        let mutable ans = 0
        ans <- if (Y >= 0) && (X = 0) then 0
               elif (Y >= 0) then 1
               else 2
        
        let aX = abs X
        let aY = abs Y
        
        ans <- ans + aX / L + (if (aX % L) = 0 then 0 else 1)
        ans <- ans + aY / L + (if (aY % L) = 0 then 0 else 1)
        
        printfn "%d" ans
        
let mySol = new Sol()
mySol.Solve()