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: Wrong Answer)

import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		Scanner scanner = new Scanner(System.in);
		int A = scanner.nextInt();
		int B = scanner.nextInt();
		int C = scanner.nextInt();
		int D = scanner.nextInt();
		int count;

//		List<Integer> alist = new ArrayList<>();
//		for (int i = 0; i <= B-A; i++) {
//			alist.add(A + i);
//		}
//
//		List<Integer> blist = new ArrayList<>();
//		for (int i = 0; i <= D-C; i++) {
//			blist.add(C + i);
//		}

		//スイッチを押している時間がかぶらない時
		if (B < C || D < A) {
			count = 0;
		//スイッチを押している時間がどちらかに含まれるとき
		} else if ((A <= C && B >= D) || (C <= A && D >= B)) {
			count = (B-A <= D-C) ? B-A : D-C;

		//スイッチを押している時間が一部かぶるとき
		} else {
			if (B == C || D == A) {
				count = 0;
			} else if (B < C) {
				count = Math.abs(C - B);
			} else {
				count = Math.abs(D - A);
			}
		}
		System.out.println(count);

	}

}