How to divide the difficulty of life and death in Go?

Utaro Hashimoto Style and Carving, this set of life and death questions is characterized by many questions, neat chess shapes, and no need for a lot of calculations, and the difficulty is around Samsung. Dragon map is a set of difficult life and death questions. Most of the chess shapes are scattered, and there are also many blind spots that are difficult to detect. The difficulty is about four stars. The last thing I want to say is the ghost hand and the magic hand. This kind of life and death is specially designed for professional chess players to train their computing ability.