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 arg[]) {
    		Scanner sc = new Scanner(System.in);
    		int A = sc.nextInt();
    		int B = sc.nextInt();
    		int C = sc.nextInt();
    		int D = sc.nextInt();
    		sc.close();
    		int[] Alice = new int[102];
    		int[] Bob = new int[102];
    		int count = 0;
    		
    		for(int i = 0; i <= 100; i++ ) {
    			if( i < A || i >= B) {
    				Alice[i] = 999;
    			}else {
    				Alice[i]= i; 
    			}
    		}
    		
    		for(int i = 0; i <= 100; i++ ) {
    			if( i < C || i >= D) {
    				Bob[i] = 998;
    			}else {
    				Bob[i]= i; 
    			} 
    		}
    		
    		for(int i = 0; i <= 100; i++) {
    			if(Alice[i] == Bob[i]) {
    				count++;
    			}
    		}
    		System.out.println(count);
    	}
    }