The rank of 7 is the first clue that whatever mystery code for transforming input to output will not be particularly complex. I looked for low-hanging fruit, and there it is. If you want to re-calibrate your horrible-ometer, try some Bongard Problems. The point is to figure out what all the things on each side (left or right) have in common, and what and how that makes them different from / opposite to all the things on the other side. gl hf

"I do not know what to smoke to come up with such a task"
LOL

I couldn't do it. I looked at the solutions and here are my feelings:

1. I do not know what to smoke to come up with such a task
2. Don't waste your time, I do not know how people find such patterns from thousands of tests.

Kinda got everything done, but I don't understand how to do a standard string check without lengthening. I'm stumped.