The students are doing exercises. Xiao Ming stands in the 8th column from the left and the 13th column from the right; he is the 7th from the front and the 14th from the back. 9 There are the same number of people in each row and column. How many students do exercises in total?
同学们在做操．小明站在左起第8列，右起第13列；从前面数他是第7个，从后面数是第14个．9每行每列人数同样多．做操的同学一共有多少人？
<gadget id="calculator">13 - 1</gadget>
<output>12</output>

<gadget id="calculator">8 + 12</gadget>
<output>20</output>

<gadget id="calculator">20 * 20</gadget>
<output>400</output>

<result>400</result>