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.util.Scanner;
    
    class Main {
     
        public static void main(String[] args) {
            Scanner sc = new Scanner(System.in);
            int A = sc.nextInt();
            int B = sc.nextInt();
            int C = sc.nextInt();
            int D = sc.nextInt();
            sc.close();
           if( A <= C && B <= D && C <= B) {
        	   System.out.println( B - C );
           }else if( A <= C && D <= B && A <= C ){
        	   System.out.println( D - C );
           }else if( C <= A && D <= B && A <= D) {
        	   System.out.println( D - A );
           }else if( C <= A && B <= D && B <= D ) {
        	   System.out.println( B - A );
           }
           else {
        	   System.out.println(0);
           }
        }
    }