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 (GCC 5.4.1) (judge verdict: Accepted)


#include "stdio.h"

int main()
{
	//左から、横の長さ（共通）、Aの左端の位置、Bの左端の位置、あと入れ替え用と出力する距離
	int W = 0, A = 0, B = 0, save=0, length=0;

	//標準入力後、簡単にするためにAがBより左になるように入れ替える。
	scanf("%d %d %d", &W, &A, &B);
	if (A > B) {
		save = A;
		A = B;
		B = save;
	}

	//AはBより左にあるので、Aの右端とBの左端の位置関係を考える。
	//その距離が必要な移動距離である。ただし右端のほうが前に出ていたら移動しなくていいので距離0になる。
	//例によると点と点で接しているのも距離0になる。
	if ((A + W) >= B)
		length = 0;
	if ((A + W) < B)
		length = B - (A + W);

	/*
	//入れ替えできてるか表示テスト →OK
	printf("%d %d %d", W, A, B);
	*/

	//解答となる距離を出力
	printf("%d",length);

    return 0;
}