3 people in each group
In the first round, in-group circulation, three people were eliminated 1 person, leaving two people, and the situation of four groups was 4*2=8 people.
Top 8 is divided into the upper part and the lower part.
In each round of semi-round robin, one point is scored for winning one game, and no point is scored for losing one game. Finally, the ranking is based on the score.