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Collections are a way for you to organize kata so that you can create your own training routines. Every collection you create is public and automatically sharable with other warriors. After you have added a few kata to a collection you and others can train on the kata contained within the collection.
Get started now by creating a new collection.
There's sometimes a problem with the client when trying to submit solutions. Refreshing the page usually solves the "unknown error" issue.
The "6000ms" error is 99% of the time due to an unoptimized algorithm. The Kata details hint at the algorithm needing to work with big numbers. Iterating through all the numbers won't work in the time constraint.
Try testing with numbers in the range mentioned in the description. Also, try testing with negative n's.