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;
using System.Threading.Tasks;

namespace ConsoleApplication2
{
    class Program
    {
        static void Main(string[] args)
        {
            //int N = int.Parse(Console.ReadLine());

            string[] tmp = Console.ReadLine().Split(' ');
            int W = int.Parse(tmp[0]);
            int a = int.Parse(tmp[1]);
            int b = int.Parse(tmp[2]);

            if (b >= a)
            {
                if (a + W >= b)
                {
                    Console.WriteLine(0);
                }
                else
                {
                    Console.WriteLine(b - (a + W));
                }

            }
            else
            {
                if (b + W >= a) Console.WriteLine(0);
                else Console.WriteLine(a - (b + W));
            }

            Console.ReadLine();


        }
    }
}