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;

class Main {
	public static void main(String[] args) throws IOException{
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		try {
			String str = br.readLine();
			String[] s = str.split(" ",0);
			int a = Integer.parseInt(s[0]);
			int b = Integer.parseInt(s[1]);
			int c = Integer.parseInt(s[2]);
			int d = Integer.parseInt(s[3]);
			int total = 0;
			if(a < c) {
				if(b < d) {
					total = b - c;
				}else {
					total = d - c;
				}
			}else {
				if(b < d) {
					total = b - a;
				}else {
					total = d - a;
				}
			}

			if(total >= 0) {
				System.out.println(total);
			}else {
				total = 0;
				System.out.println(total);
			}

//			long max  = 1000000007;
		}catch (Exception e) {
			System.exit(0);
		}
	}
}