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 (Clang 3.8.0) (judge verdict: Wrong Answer)

#include <iostream>
#include <string>
#include <vector>
#include <algorithm>
#include <utility>
#include <tuple>
#include <cstdint>
#include <cstdio>
#include <map>
#include <queue>
#include <set>
#include <stack>
#include <deque> 
#include <unordered_map>
#include <unordered_set>
#include <bitset>
#include <cctype> 
using namespace std;

int main(){
    int A, B, C, D;
    cin >> A >> B >> C >> D;
    if (A<C && D<B) {
        cout << D-C << endl;
        return 0;
    }
    else if (C<A && B<D) {
        cout << B-A << endl;
        return 0;
    }
    else if (B>C && D>B) {
        cout << B-C << endl;
        return 0;
    }
    else if (A<D && C<A) {
        cout << D-A << endl;
        return 0;
    }
    else if (A<C && C<B) {
        cout << B-C << endl;
        return 0;
    }
    else if (A<D && D<B) {
        cout << D-A << endl;
        return 0;
    }
    else cout << 0 << endl;
}