During the gymnastics competition, Class 51 stood in a square. Xiaohong found that the fifth person from the front, back, left and right was herself. How many students did Xiaohong have in class?
在体操比赛活动中，五1班站成一个正方形，小红发现从前、后、左、右数起第5个都是自己，小红班共有多少名同学．
<gadget id="calculator">5 * 2</gadget>
<output>10</output>

<gadget id="calculator">10 - 1</gadget>
<output>9</output>

<gadget id="calculator">9 * 9</gadget>
<output>81</output>

<result>81</result>