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 Kotlin (1.0.0) (judge verdict: Accepted)

  fun main(args: Array<String>) {
    val (A,B,C,D) = readLine()!!.split(" ").map{ i -> i.toInt() }
    var result = 0;
    if(B<=C || D<=A) {result = 0}
    else if(A<=C && D<=B) {result = Math.abs(C - D)} 
    else if(C<=A && B<=D) {result = Math.abs(A - B)}
    else if(A>=C && D<=B) {result = Math.abs(A - D)} 
    else if(C>=A && B<=D) {result = Math.abs(C - B)} 
    println(result)
}