The students are doing exercises. Xiaoli is standing 12th from the left, 8th from the right, 5th from the front, and 16th from the back. Each row has the same number of people, and each column has the same number of people. How many students are doing exercises in total?
同学们做操，小丽站在从左起数第12个，从右数起第8个，从前面数是第5个，从后数是第16个．每行的人数同样多，每列的人数也同样多．一共有多少名同学在做操？
<gadget id="calculator">8 - 1</gadget>
<output>7</output>

<gadget id="calculator">12 + 7</gadget>
<output>19</output>

<gadget id="calculator">16 - 1</gadget>
<output>15</output>

<gadget id="calculator">5 + 15</gadget>
<output>20</output>

<gadget id="calculator">19 * 20</gadget>
<output>380</output>

<result>380</result>