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 Rust (1.15.1) (judge verdict: Accepted)

#[allow(unused_imports)]
use std::io;
use std::io::stdin;

fn read_line_as_vec() -> Vec<String> {
    let mut s = String::new();
    stdin().read_line(&mut s).expect("");
    s.split(' ').map(|x| x.to_string()).collect::<Vec<String>>()
}

fn main() {
    let wab = read_line_as_vec();
    let w: u32 = wab[0].trim().parse().expect("");
    let mut a: u32 = wab[1].trim().parse().expect("");
    let mut b: u32 = wab[2].trim().parse().expect("");
    if a > b {
        std::mem::swap(&mut a, &mut b);
    }
    println!("{}", b.saturating_sub(a + w));
}