Problem:
Score : 200 points

Problem Statement

AtCoDeer the deer found two rectangles lying on the table, each with height 1 and width W.
If we consider the surface of the desk as a two-dimensional plane, the first rectangle covers the vertical range of [0,1] and the horizontal range of [a,a+W], and the second rectangle covers the vertical range of [1,2] and the horizontal range of [b,b+W], as shown in the following figure:

AtCoDeer will move the second rectangle horizontally so that it connects with the first rectangle.
Find the minimum distance it needs to be moved.

Constraints

All input values are integers.

1≤W≤10^5

1≤a,b≤10^5

Input

The input is given from Standard Input in the following format:

W a b

Output

Print the minimum distance the second rectangle needs to be moved.

Sample Input 1

3 2 6

Sample Output 1

1

This input corresponds to the figure in the statement. In this case, the second rectangle should be moved to the left by a distance of 1.

Sample Input 2

3 1 3

Sample Output 2

0

The rectangles are already connected, and thus no move is needed.

Sample Input 3

5 10 1

Sample Output 3

4

Solution in Scala (2.11.7) (judge verdict: Accepted)

import scala.io.StdIn

object Main extends App {

  val Array(w, a, b) = StdIn.readLine().split(" ").map(_.toInt)
  // a1
  // a2 = w + a
  // b1
  // b2 = w + b
  val (a1, a2, b1, b2) = (a, a + w, b, b + w)
  // a1 <= b1 <= a2 || 
  // a1 <= b2 <= a2    => 0

  // a2 < b1 => b1 - a2
  // b2 < a1 => b2 - a1
  val r = if ((a1 <= b1 && b1 <= a2) || (a1 <= b2 && b2 <= a2)) 0
  else if (a2 < b1) b1 - a2
  else a1 - b2
  println(r)
}