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;

public class Main {

    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
//        int n = Integer.parseInt(br.readLine());
        String[] str = br.readLine().split(" ");

        int[] t = new int[101];
        int a = Integer.parseInt(str[0]);
        int b = Integer.parseInt(str[1]);
        int c = Integer.parseInt(str[2]);
        int d = Integer.parseInt(str[3]);

        t[a] += 1;
        t[b] -= 1;
        t[c] += 1;
        t[d] -= 1;

        for (int i = 1; i < 101; i++) {
            t[i] += t[i - 1];
        }

        int cnt = 0;
        for (int i = 0; i < 101; i++) {
            if (t[i] == 2) cnt++;
        }
        System.out.println(cnt);

    }
}