The third grade students line up in a rectangular team to do exercises. Xiao Ming stands in the team, the 9th from the left and the 10th from the right. He is the 11th from the front and the 12th from the back. How many are there in the third grade? Do people do exercises?
三年级同学排成长方形队伍做操，小明站在队伍中左起第9个，右起第10个，从前边数他是第11个，从后边数他是第12个，三年级一共有多少人做操？
<gadget id="calculator">10 - 1</gadget>
<output>9</output>

<gadget id="calculator">9 + 9</gadget>
<output>18</output>

<gadget id="calculator">12 - 1</gadget>
<output>11</output>

<gadget id="calculator">11 + 11</gadget>
<output>22</output>

<gadget id="calculator">18 * 22</gadget>
<output>396</output>

<result>396</result>