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 <cstring>
#include <ctime>
#include <cstdlib>
#include <cmath>
#include <iostream>
#include <string>
#include <queue>
#include <map>
#include <stack>
#include <vector>
#include <algorithm>
#include <set>
#include <deque>
#include <utility>
#include <chrono>
#include <sstream>
#include <iomanip>
#define INF 1 << 30
#define MOD 1000000007;
#define D(x) cout << x << endl
#define d(x) cout << x
#define all(x) (x).begin(), (x).end()
#define pb(x) push_back(x)
#define pf(x) push_front(x)
#define mp(x) make_pair(x)
using namespace std;
typedef long long ll;
typedef vector<int> vi;
typedef vector<long long> vll;
typedef pair<int, int> pii;
template<typename T, typename U> inline void amin(T &x, U y) { if (y < x) x = y; }
template<typename T, typename U> inline void amax(T &x, U y) { if (x < y) x = y; }
static const int dx[] = {0, 0, 1, -1};
static const int dy[] = {-1, 1, 0, 0};

int main() { 
  int w, a, b;
  cin >> w >> a >> b;
  if (a > b) {
    swap(a, b);
  }
  D(max(0, b - a - w));
  return 0;
}