Who are the four representatives of calligraphers in Song Dynasty?

In fact, Song Sijia can become five Song Dynasties.

There were Cai Jing, Su Shi, Mi Fei and Huang Tingjian in early Song Sijia.

Later, because Cai Jing was listed as a corrupt official and replaced by Cai, Su Shi became the boss, Mi Fei was the second, Huang Tingjian was the third, and Cai Xiang's calligraphy was only the last.

Personally, I like Dongpo because of my sin, hehe.