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.
Your function returns 7745 instead of 7547, print the input. It could be 7475.
It should work for random inputs too: 7745 should equal 7547 , but next bigger number should be 7754. 7547 < 7745