5 rows and 5 columns 1 * * *, 25 people. Excluding the first two rows and the first two columns 16 people, there are 9 people left. Of these nine people, five are in the fifth row or the fifth column but not in the first two rows or the first two columns, so five are tangled.

The ranks of class seats are generally from left to right and from front to back. The key is to see if the rows and columns in everyone's mind are certain.