Loading collection data...
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.
From the description:
"The path ["NORTH", "WEST", "SOUTH", "EAST"] is not reducible."
For that case, the input and output should be the same.
Apparently you do not understand task well ;)
Not a kata issue. Description mentions several times that only directions immediately following one another can be reduced.