Time limit: 0.5 seconds Memory limit: 64 megabytes --- An exam hosting system opens from minute $s$ until minute $f$. The maximum duration for answering the questions is $l$ minutes. A person enters the system at moment $x$. + If the entrance request is before the exam starts (before moment $s$), print the message `exam did not started!`. + If the entrance request is after the exam finishes (at moment $f$ or after it), print the message `exam finished!`. + Otherwise, print the time (in minutes) the person has to answer the questions. Note that the exam hosting system might close (before the $l$ minutes end), but the person's allowed response time might remain. # Input In the single line of input, four natural numbers $s$, $f$, $l$, and $x$ are given, separated by a space. $$1 \le s < f \le 100$$ $$1 \le l \le \min\{20, f - s\}$$ $$1 \le x \le 100$$ # Output In the single line of output, print the requirement of the problem. # Example ## Sample Input 1 ``` 20 40 10 36 ``` ## Sample Output 1 ``` 4 ``` The exam hosting system is open in the time interval 20 to 40. If a person enters the system at moment 36 and wants to participate in an exam that lasts 10 minutes, they only have 4 minutes because the system will close after 4 minutes. ## Sample Input 2 ``` 20 40 10 40 ``` ## Sample Output 2 ``` exam finished! ``` The exam hosting system is open in the time interval 20 to 40. If a person enters the system at moment 40, they have no opportunity to answer because the exam is finished. ## Sample Input 3 ``` 20 40 10 19 ``` ## Sample Output 3 ``` exam did not started! ``` The exam hosting system is open in the time interval 20 to 40. If a person enters the system at moment 19, we must inform them that the exam has not started yet.