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 C++14 (GCC 5.4.1) (judge verdict: Accepted)

#include <bits/stdc++.h>
using namespace std ;
int main() {
    int x=0;
    int A,B,C,D;
    cin>>A>>B>>C>>D;
    if(A>=0&&C>=0&&A<B&&C<D&&B<=100&&D<=100){
        if(A<C){
            if(B>D){
                x=C-D;
            }
            else if(D>B){
                if (B>C){
                    x=C-B;
                }
            }
            else{
                x=C-B;
            }

        } else if (A>C){
             if(B>D){
                 if(D>A)
                 x=A-D;
             }else if(D>B){
                 if(B>C){
                     x=A-B;
                 }
             }else{
                 x=A-B;
             }
        }else{
            if(B>D){
                x=A-D;
            }else if(B<D){
                x=A-B;
            } else{
                x=A-B;
            }
        }

 printf("%d",abs(x));
    }
    return 0;
}