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 Java8 (OpenJDK 1.8.0) (judge verdict: Accepted)

import java.io.IOException;
import java.io.InputStream;
import java.util.Arrays;
import java.util.NoSuchElementException;


public class Main {
    public static void main(String[] args) {
        FastScanner sc = new FastScanner();
        int w = sc.nextInt();
        int a = sc.nextInt();
        int b = sc.nextInt();
        if ((a <= b && b <= a+w) || (a <= b+w && b+w <= a+w)) {
            System.out.println(0);
        } else {
            System.out.println(Math.min(Math.abs(b-(a+w)), Math.abs(a-(b+w))));
        }
    }
}


class FastScanner {
    public static String debug = null;

    private final InputStream in = System.in;
    private int ptr = 0;
    private int buflen = 0;
    private byte[] buffer = new byte[1024];
    private boolean eos = false;

    private boolean hasNextByte() {
        if (ptr < buflen) {
            return true;
        } else {
            ptr = 0;
            try {
                if (debug != null) {
                    buflen = debug.length();
                    buffer = debug.getBytes();
                    debug = "";
                    eos = true;
                } else {
                    buflen = in.read(buffer);
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
            if (buflen < 0) {
                eos = true;
                return false;
            } else if (buflen == 0) {
                return false;
            }
        }
        return true;
    }

    private int readByte() {
        if (hasNextByte())
            return buffer[ptr++];
        else
            return -1;
    }

    private static boolean isPrintableChar(int c) {
        return 33 <= c && c <= 126;
    }

    private void skipUnprintable() {
        while (hasNextByte() && !isPrintableChar(buffer[ptr]))
            ptr++;
    }

    public boolean isEOS() {
        return this.eos;
    }

    public boolean hasNext() {
        skipUnprintable();
        return hasNextByte();
    }

    public String next() {
        if (!hasNext())
            throw new NoSuchElementException();
        StringBuilder sb = new StringBuilder();
        int b = readByte();
        while (isPrintableChar(b)) {
            sb.appendCodePoint(b);
            b = readByte();
        }
        return sb.toString();
    }

    public long nextLong() {
        if (!hasNext())
            throw new NoSuchElementException();
        long n = 0;
        boolean minus = false;
        int b = readByte();
        if (b == '-') {
            minus = true;
            b = readByte();
        }
        if (b < '0' || '9' < b) {
            throw new NumberFormatException();
        }
        while (true) {
            if ('0' <= b && b <= '9') {
              n *= 10;
              n += b - '0';
            } else if (b == -1 || !isPrintableChar(b)) {
                return minus ? -n : n;
            } else {
                throw new NumberFormatException();
            }
            b = readByte();
        }
    }

    public int nextInt() {
        return (int) nextLong();
    }

    public long[] nextLongList(int n) {
        return nextLongTable(1, n)[0];
    }

    public int[] nextIntList(int n) {
        return nextIntTable(1, n)[0];
    }

    public long[][] nextLongTable(int n, int m) {
        long[][] ret = new long[n][m];
        for (int i = 0; i < n; i ++) {
            for (int j = 0; j < m; j ++) {
                ret[i][j] = nextLong();
            }
        }
        return ret;
    }

    public int[][] nextIntTable(int n, int m) {
        int[][] ret = new int[n][m];
        for (int i = 0; i < n; i ++) {
            for (int j = 0; j < m; j ++) {
                ret[i][j] = nextInt();
            }
        }
        return ret;
    }
}