*looks drowsy* Ugh my head..

You know what, guys? If you can freshly and directly remember how to do this:

- calculate the time complexity for each type of loop and code structure

- knowing how to write the following regex:
"A 15-digit number starting with a possibility of a group of 1-2 digit numbers, segregated into three 5-digit numbers tuples with three different separator characters, evaluated ahead"

- mentally work out how to reverse an array's indexes (swapping algorithm) without writing anything down

- know how to optimize a binary search in your head

then kudos to you. lmao
I'm rusty. It took me a while..