Sorry if I explained myself wrong :(
The key-subject I told you about above is the name of an item/object/person/environment that your photo contains. If you win, I will add the key-subject as one of the 2 key-subject in the next edition.
An example: for your photo, some perfect key-subjects would be monastery, or religion, or church, or cat.
I hope you can understand from what I wrote above: I know, the rules are a few complicated, but the functioning is the same with which I started the challenge, and blockchain's functioning rules-based