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 (GCC 5.4.1) (judge verdict: Wrong Answer)

#include<stdio.h>
#include<string.h>

int main(){
  
  int A,B,C,D;
  scanf("%d %d %d %d",&A,&B,&C,&D);
  int numA[100]={0};
  int numC[100]={0};
  int result = 0;

  for(int i=A; i<=B; i++){
    numA[i]++;
  }

  for(int i=C; i<=D; i++){
    numC[i]++;
  }

  for(int i=1; i<=100; i++){
    if(numA[i] == 1 && numC[i] == 1 ){
      result ++;
    }
  }

  if( result == 0){
    printf("0");
  }else{
    printf("%d",result-1);
  }

  return 0;

}