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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.
That's out of the spec of this kata, and also something you should think about yourself ;-)
if the identifers of these operators are not the orignals but "a"、"ab"、"abc"、"abcd" or something that you can not identify by the initial,how to sove this kata?