The students participating in the military training lined up in a square queue to perform. If this queue was increased by one row horizontally and vertically, 21 more people would be needed. How many students are there in the cohort performance?
参加军训的学生排成了一个正方形队列进行表演，如果这个队列横竖各增加一排，还需要补充21人．参加队列表演的学生有多少人？
<gadget id="calculator">21 + 1</gadget>
<output>22</output>

<gadget id="calculator">22 / 2</gadget>
<output>11</output>

<gadget id="calculator">11 * 11</gadget>
<output>121</output>

<gadget id="calculator">121 - 21</gadget>
<output>100</output>

<result>100</result>