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 C# (Mono 4.6.2.0) (judge verdict: Accepted)

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
class Program
{
    static void Main(string[] args)
    {
            // 入力
            string[] sS = Console.ReadLine().Trim().Split(' ');
            int iWid = int.Parse(sS[0]);                            // 幅
            int iAx1 = int.Parse(sS[1]);                            // Aの左端
            int iBx1 = int.Parse(sS[2]);                            // Bの左端

            System.Diagnostics.Stopwatch sw = new System.Diagnostics.Stopwatch();
            sw.Start();

            // 解析
            int iAx2 = iAx1 + iWid;                                 // Aの右端
            int iBx2 = iBx1 + iWid;                                 // Bの右端
            int iOut = 0;                                           // 移動量
            Boolean bLnk = false;                                   // 連結状態
            if (iAx1 <= iBx1 && iBx1 <= iAx2) { bLnk = true; }      // Aの範囲にBの左端がある場合は連結
            if (iAx1 <= iBx2 && iBx2 <= iAx2) { bLnk = true; }      // Aの範囲にBの右端がある場合は連結
            if (!bLnk)                                              // 連結していない場合
            {
                Boolean bRig = false;                               // BがAの右にあるフラグ
                if (iAx1 < iBx1) { bRig = true; }                   // BがAの右にある場合
                if (bRig) { iOut = iBx1 - iAx2; }                   // Bの左端をAの右端まで移動(BがAの右にある場合)
                else { iOut = iAx1 - iBx2; }                        // Bの右端をAの左端まで移動(BがAの左にある場合)
            }

            //出力
            Console.WriteLine("{0}", iOut.ToString().Trim());

            sw.Stop();
#if DEBUG
            Console.WriteLine();
            Console.WriteLine("{0}", sw.Elapsed.ToString());
            Console.WriteLine("続行するには何かキーを押してください．．．");
            Console.ReadKey();
#endif
    }
}