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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.
In this kata, a difference seems to be defined as non-negative integer. So, there are no pairs when a negative n is given. And also, think carefully for n==0 case (e.g. lst=[1,1,1],n=0). When you want to check the input values, try to add a temporary code like "print(lst,n)"