How do "First level" and "Last level" work?

The book climbs from the first level to the last in equal parts. With Easy to Evil and 200 puzzles, there are 40 Easy, 40 Medium, 40 Hard, 40 Expert and 40 Evil puzzles, in that order. Inside each level the puzzles print from the gentlest to the toughest, so puzzle 1 is never harder than puzzle 2 of the same level. For a book of one level only, choose the same level twice.