Just insane. I have research to do.

I wish I would have seen this comment before starting. The random tests throw massive numbers at you that no standard rust type can hold. Rust is strongly typed, so this number is required to be parsed in order to add 1 to it. It's extremely annoying that the description does not tell you that you're screwed.

Luckily, you can use num::BigUint; and that can hold these numbers. I had to look at the solutions to know this, so bye-bye any rank I might have gotten. At least I know how to import Bigint now.

How might you interpret a number as negative?
foo-001 could easily be seen as the number "001" after the string "foo-"

That bitwise AND trick is neat. Will have to remember it.

The first run only uses 3 entries. Note the take(3) call.

That comparison method is genius and I'll have to remember that.

As well, it begins by completely copying word.

Watch for any "use" keywords. Indeed, sorted() needs the Itertools crate.