Problem:
Score : 200 points

Problem Statement

Alice and Bob are controlling a robot. They each have one switch that controls the robot.

Alice started holding down her button A second after the start-up of the robot, and released her button B second after the start-up.

Bob started holding down his button C second after the start-up, and released his button D second after the start-up.

For how many seconds both Alice and Bob were holding down their buttons?

Constraints

0≤A<B≤100

0≤C<D≤100

All input values are integers.

Input

Input is given from Standard Input in the following format:

A B C D

Output

Print the length of the duration (in seconds) in which both Alice and Bob were holding down their buttons.

Sample Input 1

0 75 25 100

Sample Output 1

50

Alice started holding down her button 0 second after the start-up of the robot, and released her button 75 second after the start-up.

Bob started holding down his button 25 second after the start-up, and released his button 100 second after the start-up.

Therefore, the time when both of them were holding down their buttons, is the 50 seconds from 25 seconds after the start-up to 75 seconds after the start-up.

Sample Input 2

0 33 66 99

Sample Output 2

0

Alice and Bob were not holding their buttons at the same time, so the answer is zero seconds.

Sample Input 3

10 90 20 80

Sample Output 3

60

Solution in Java8 (OpenJDK 1.8.0) (judge verdict: Accepted)

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class Main {

  public static void main(String[] args) {

    int a = 0;
    int b = 0;
    int c = 0;
    int d = 0;
    String[] tmp = null;
    try (BufferedReader br = new BufferedReader(new InputStreamReader(System.in))) {
      tmp = br.readLine().split("\\s");
      a = Integer.parseInt(tmp[0]);
      b = Integer.parseInt(tmp[1]);
      c = Integer.parseInt(tmp[2]);
      d = Integer.parseInt(tmp[3]);
    } catch (IOException e) {
      e.printStackTrace();
      System.exit(1);
    }

    int start = 0;
    int end = 0;

    if (a < c) {
      start = c;
    } else {
      start = a;
    }

    if (b < d) {
      end = b;
    } else {
      end = d;
    }

    int result = end - start;
    if (result < 0) {
      result = 0;
    }
    System.out.print(result);

  }
}