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;
using System.Diagnostics;



namespace VS_TopCoder
{
    class Chokuho
    {
        public int X { get; set; }
        public int Y { get; set; }
        public int Z { get; set; }
        public int W { get; set; }
        public int H { get; set; }
        public int V { get; set; }
    }


    class Program
    {

        static void Main(string[] args)
        {
            Test();


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

            int sa1 = a + W - b;
            int sa2 = b + W - a;

            //bがaの間に入っていた場合
            if (b >= a && b <= a+W)
            {
                Console.WriteLine(0);
            }
            //b+Wがaの間に入っていた場合
            else if (b+W >= a && b+W <= a + W)
            {
                Console.WriteLine(0);
            }
            else
            {
                Console.WriteLine(Math.Min(Math.Abs(sa1),Math.Abs(sa2)));
            }




        }


        static List<string> Readlines()
        {
            List<string> answer = new List<string>();

            do
            {
                var item = Console.ReadLine();
                if (item == null)
                {
                    break;
                }
                else
                {
                    answer.Add(item);
                }
            } while (true);

            return answer;
        }

        static List<string[]> Readlines2D(string divider)
        {
            List<string[]> answer = new List<string[]>();

            do
            {
                var item = Console.ReadLine();
                if (item == null)
                {
                    break;
                }
                else
                {
                    answer.Add(item.Split(Convert.ToChar(divider)));
                }
            } while (true);

            return answer;
        }

        //priority queue


        [Conditional("DEBUG")]
        static private void Test()
        {
            Console.SetIn(new System.IO.StreamReader(@"c:\users\user\documents\visual studio 2015\Projects\VS TopCoder\VS TopCoder\Test.txt"));
        }
    }
    class PriorityQueue<T>
    {
        private readonly List<T> heap;
        private readonly Comparison<T> compare;
        private int size;
        public PriorityQueue() : this(Comparer<T>.Default) { }
        public PriorityQueue(IComparer<T> comparer) : this(16, comparer.Compare) { }
        public PriorityQueue(Comparison<T> comparison) : this(16, comparison) { }
        public PriorityQueue(int capacity, Comparison<T> comparison)
        {
            heap = new List<T>(capacity);
            compare = comparison;
        }
        public void Enqueue(T item)
        {
            heap.Add(item);
            var i = size++;
            while (i > 0)
            {
                var p = (i - 1) >> 1;
                if (compare(this.heap[p], item) <= 0)
                    break;
                this.heap[i] = heap[p];
                i = p;
            }
            this.heap[i] = item;

        }
        public T Dequeue()
        {
            var ret = this.heap[0];
            var x = this.heap[--size];
            var i = 0;
            while ((i << 1) + 1 < size)
            {
                var a = (i << 1) + 1;
                var b = (i << 1) + 2;
                if (b < size && compare(heap[b], heap[a]) < 0) a = b;
                if (compare(heap[a], x) >= 0)
                    break;
                heap[i] = heap[a];
                i = a;

            }
            heap[i] = x;
            heap.RemoveAt(size);
            return ret;
        }

        public T Peek() { return heap[0]; }
        public int Count { get { return size; } }
        public bool Any() { return size > 0; }



    }


}