Score : $200$ points
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?
Input is given from Standard Input in the following format:
$A$ $B$ $C$ $D$
Print the length of the duration (in seconds) in which both Alice and Bob were holding down their buttons.
0 75 25 100
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.
0 33 66 99
0
Alice and Bob were not holding their buttons at the same time, so the answer is zero seconds.
10 90 20 80
60