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.Linq;
using System.Numerics;
using System.Collections.Generic;
using System.Text;
using System.Threading.Tasks;
using System.IO;
using System.Diagnostics;
using System.Text.RegularExpressions;

namespace CsTest
{
    class Program
    {
        static void Main()
        {
            var Wab = AtCoder.ReadInt64Array();
            var W = Wab[0];
            var a = Wab[1];
            var b = Wab[2];

            long ret = a <= b ? MoveLength(W, a, b) : MoveLength(W, b, a);

            Console.WriteLine(ret);
        }

        static long MoveLength(long W, long s, long l)
        {
            if (s + W >= l) return 0;
            else return l - s - W;
        }
    }

    public class AtCoder
    {
        public static string[] ReadStringArray() => Console.ReadLine().Split(Array.Empty<char>(), StringSplitOptions.RemoveEmptyEntries);
        public static int[] ReadInt32Array() => ReadStringArray().Select(s => int.Parse(s)).ToArray();
        public static long[] ReadInt64Array() => ReadStringArray().Select(s => long.Parse(s)).ToArray();
    }
}