In the first round, each ball was assigned a number,1v2.3v4.5v 6.7v8.9v10.
In the second round, five winners rent 1.2.3.4.5 to A, and five losers rent 6.7.8.9.10 to B..A bye 1V2 3V4 5 (who can be decided by drawing lots). Similarly, team B is the same, 6V7 8V9 10 Bye.
In the third round, the winning team in Group A was promoted directly, and the losing team was reduced to Group B, while the winning team in Group B was retained and the losing team was eliminated directly. Then there are three teams left in Group A and five teams left in Group B, and then Group A has a bye 1V2.3 (you can draw lots to decide who has a bye). Group b bye 1V2 3V4 5 (you can draw lots to decide who is bye).
In the fourth round, the winning team in Group A was promoted directly, and the losing team was reduced to Group B, while the winning team in Group B was retained and the losing team was eliminated directly. There are two teams left in Group A, and four teams left in Group B. Group A: 1V2. Victory goes straight to the final. Group b, team 4, 1V2 3V4.
In the fifth round, there is one team left in Group A, three teams left in Group B, and Group B has a bye 1V2.3 (you can draw lots to decide who has a bye).
There is one team left in Group A in the sixth round. There are two teams left in Group B. The winner of 1V2 enters the final and the loser wins the third place.
There is one team left in Group A in the seventh round. There is another team in Group B, AVB. Decide the first and second team.
I believe 18 will be wonderful. . .