let calc x y r =
    let a = x + y
    let list = [ a .. (min (3 * (x + y + r) / 2) 342) ]

    (List.filter (fun i -> 2 * r * r - (x + y - i) * (x + y - i) < 0) list).[0]


let main =
    let input = stdin.ReadLine().Split() |> Array.map int
    let x = input[0]
    let y = input[1]
    let r = input[2]

    printf "%d\n" (calc (abs (x)) (abs (y)) r)