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 <iostream>
#include <iomanip>
#include <fstream>
#include <sstream>
#include <vector>
#include <algorithm>
#include <math.h>
#include <map>
#include <set>
#include <queue>
#include <deque>
#include <stack>
#include <bitset>

#define _GLIBCXX_DEBUG
#define rep(i, n) for (int64_t i = 0; i < (int64_t)(n); i++)
using namespace std;
using vi = vector<int64_t>;
using vvi = vector<vi>;

int main(int argc, const char * argv[]) {
    // fasten cin
    cin.tie(0);
    ios::sync_with_stdio(false);
    // implement
    int64_t w,a,b;
    cin >> w >> a >> b;
    if(b>a){
        cout << (b-a-w>=0?b-a-w:0) << endl;
    }else{
        cout << (a-b-w>=0?a-b-w:0) << endl;
    }
}