Got it but my problem remains: I don't understand what is the "trick". I just try several routes and eventually one is the right one, but I can't identify what makes it the winning one.
Wasn't completely sure, but my 1st try to 26 proved correct. :)
Edit: And there are two slightly different solutions. It's the same main idea, but the order can be in two ways. Maybe this helps somebody, to solve it. :)
