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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.
Please use a spoiler flag when you give hints to a solution (I've just put the flag on for you).
Your approach is very expensive. Consider carefully all the data of the problem, you are doing much more work than actually needed.