The students lined up in a square matrix, and later reduced the number of rows to a total of 19 people. How many people were there?
同学们排成了一个正方形方阵，后来减少了一行一列共19人．原来共有多少人？
<gadget id="calculator">19 + 1</gadget>
<output>20</output>

<gadget id="calculator">20 / 2</gadget>
<output>10</output>

<gadget id="calculator">10 * 10</gadget>
<output>100</output>

<result>100</result>