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++14 (GCC 5.4.1) (judge verdict: Accepted)

#include<cstdio>
#include<cstdlib>
#include<cmath>
#include<iostream>
#include<algorithm>

using namespace std;

const int Max = 1e9 + 7;
typedef long long ll;
ll ans;

int main(){
	int a, b, w, ans, A, B;
	while(~scanf("%d %d %d", &w, &a, &b)){
		A = a + w, B = b + w;
		if(A <= b)  ans = b - A;
		if(A > b && A <= B)  ans = 0;
		if(A > B){
			if(a < B) ans = 0;
			else ans = a - B;
		}
		cout << ans << endl;
	}
	return 0;
}