My program keeps getting internal error. What am i doing wrong?
If you get an internal error this is not due to anything you have done - it is an error on the CodeChef server. You may need to just try again later; alternatively, sometimes it will display an internal error but you will still be able to see the result of your submission by clicking on the My Submissions link on the problem page.
what is internal error occurred in the system?
Most of the time it is due to unstable internet connection. Check your connection once, probably by opening some link in different tab, then try again.