I wrote that the program digs normally in the extreme castles (the first and the last). But on a map where every penny counts, digging in them is an unaffordable luxury. And the fact that the program could have been improved is obvious to me; the author just created something like this, which is a complete waste of nerves. Maybe there are alternatives on other resources. Just now, I was trying to get it to dig, and then, lo and behold, it dug in the neighboring castle! Luckily, it still reaches the desired location.