What are the three phases of a gymnast's preparation?

I - The first phase lasts until the age of 10 and focuses on discovering the gymnast's physical abilities and teaching the technical fundamentals of the sport.
II - The second phase lasts from the age of 10 to 15 and includes a period of specialized preparation, teaching of more complex movements, and training of movements and combinations of greater difficulty.
III - The third phase lasts from the age of 16 to 19 and focuses on the finalization of physical preparation and the training of elements of great difficulty.