open System
open System.Collections.Generic

[<AutoOpen>]
module Cin =
    let read f = stdin.ReadLine() |> f
    let reada f = stdin.ReadLine().Split() |> Array.map f
    let readChars() = read string |> Seq.toArray
    let readInts() = readChars() |> Array.map (fun x -> Convert.ToInt32(x.ToString()))

[<AutoOpen>]
module Cout =
    let writer = new IO.StreamWriter(new IO.BufferedStream(Console.OpenStandardOutput()))
    let print (s: string) = writer.Write s
    let println (s: string) = writer.WriteLine s
    let inline puts (s: ^a) = string s |> println

let main() =
    let arr = reada int64
    let [| a; b; c |] = arr
    let nax = Array.max arr
    let na = max a c
    let ni = min a c
    match nax = b with
    | true ->
        let x = abs (na - ni)
        let y = abs (na - b) + 1L
        min x y
    | false ->
        let x = abs (na - b) + 1L
        let y = abs (ni - b)
        let z = abs (na - ni)
        List.min [ x; y; z ]
    |> puts
    ()

main()
writer.Close()