Tree Painting - A proposed New Problem

Dear Clive, thanks a lot, it's live now :)

It just so happened I opened mailbox to share to you some recent thoughts and your message jumped immediately.

Thank you! Whenever there is a new CSFPython problem, I wonder where on the scale between ‘easy’ and ‘will make you think about it at the strangest times for the next few days or weeks’ it will come down. This one is - luckily - on the easier side.

Thanks for a fun problem, Clive!

Interestingly enough, this one can be solved without actually traversing the tree.