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 static System.Console;
using System.Linq;
using System.IO;

namespace ConsoleApp2
{
    class Program {
        static decimal C(int a,int b) {
            decimal res = 1;
            for (int i = 0; i < b; i++) {
                res *= (a - i);
                res /= (i + 1);
            }
            return res;
        }


        static void Main(string[] Args) {
            var lis = new List<string>(ReadLine().Split(' ')).Select(int.Parse).ToList();

            if (lis[0] + lis[1] >= lis[2] && lis[0] + lis[2] >= lis[1])
                WriteLine(0);
            else
                WriteLine(
                    Math.Min(
                        Math.Max(Math.Abs(lis[2] - lis[1] - lis[0]), 0),
                        Math.Max(Math.Abs(lis[1] - lis[0] - lis[2]), 0)
                        )
                    );
            

            ProgramEndPointLabel:;

            ReadLine();
        }
    }
}