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 Java (OpenJDK 11.0.6) (judge verdict: Accepted)

import java.util.*;
import java.io.*; 

public class Main {

	public static void main (String[] args) throws IOException
	{
	    
		BufferedReader br= new BufferedReader (new InputStreamReader(System.in) );
		StringTokenizer st = new StringTokenizer(br.readLine());
		
		int[] A= new int[2];
		int[] B  = new int[2];
		int max_low=0;
		int min_high=0;
		
		A[0] = Integer.parseInt(st.nextToken());
        A[1] = Integer.parseInt(st.nextToken());
        B[0] = Integer.parseInt(st.nextToken());
        B[1] = Integer.parseInt(st.nextToken());
		
		max_low=Math.max(A[0],B[0]);
		min_high= Math.min(A[1],B[1]);
		
		if (max_low>min_high)
			System.out.println("0");
		
		else
			System.out.println(min_high-max_low);
		
		
	}
}