With the indirect method, it should be calculated as follows: first calculate the total, then subtract those who attended physical education class in the first quarter, and then subtract those who attended math classes in the last quarter. But in this way, the number of people assigned to physical education class in the first class and math class in the last class will be reduced by two times, so it needs to be doubled.

So it should be general-the first class is arranged in physical education class-the last class is arranged in math class+the first class is arranged in physical education class, and the last class is arranged in math class.

The total number is p (6 6,6) = 6× 5× 4× 3× 2×1= 720.

In the first section, the ranking of physical education class is P (5 5,5) = 5× 4× 3× 2×1=120.

The last math class is P (5 5,5) = 5× 4× 3× 2×1=120.

Physical education class was arranged in the first section, and math class was arranged in the last section. P (4，4) = 4× 3× 2× 1 = 24。

Therefore, there is an arrangement of 720-120-120+24 = 504, which excludes physical education in the first section and mathematics in the last section.