1, write the number of 16 in advance, and divide the team of 13 into four groups by drawing lots, some with four teams and some with three teams;
2. In the group, PK can be conducted separately between every two groups, and the winning two groups will enter the next round, leaving eight at last;
3. You can also compete once in each group and keep the top two in the order of points; Those with the same points will participate in the play-offs, or draw lots to decide;