[omk3]

I don't know whether to feel proud or rather slow

They funny thing is

Spoiler:

I almost got the right answer by accident, because after experimenting with halfs and failing, I started to experiment with 1/3s but gave up.
I had thought of course that the smallest the first distance the better, but I couldn't arrive at a formula. I still don't entirely get how you end up with the 4/3 distance from the first cache to the second. I'm sure I'll get it when my head is a bit clearer, it now needs some rest. I really should have progressed more quickly on this one.

Oh, well, many thanks for the puzzles and congratulations on making me obsess about them