As someone learning rust and currently going through this, I would consider that a trivial program. You will know once you get there because you hit kind of a w

As someone learning rust and currently going through this, I would consider that a trivial program. You will know once you get there because you hit kind of a wall where you have to learn and understand what is basically a language inside of a language. And the language is kind of this mapping for logic that only used to be inside of your head (ownership logic), and so translating that fluently into this brand new language is a real roadblock. The ownership model isn't too bad for strings, but those are easily the most simple way to start using the ownership model. At least for me, getting into the more advanced ownership stuff is a whole different beast entirely.