What age group does the junior high school final limit refer to?

Initial limit: the first 25 years of life. Middle age: 26-50 years old. Final age: 50- 100 years old.

This fate is that human nature is impetuous, outspoken, brilliant, not bullying good, not afraid of evil, always doing things resolutely, generous, unable to gather wealth, ruined ancestors, and six brothers and six relatives are unable to work hard and rely on themselves. The initial limit of 256 years was unsuccessful, and 2789 was lucky, just like a dead tree meets spring. The middle limit was 49 years old, and the iron mirror was re-ground, and the moon was full, 567.