The students lined up in a square team to do a group dance. Counting from front, back, left and right, Wang Yu was the fifth. How many people are there in the group dance?
同学们排成方形的队伍跳集体舞，从前、后、左、右数，王玉都是第5个．跳集体舞的共有多少人．
<gadget id="calculator">5 - 1</gadget>
<output>4</output>

<gadget id="calculator">5 + 4</gadget>
<output>9</output>

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

<result>81</result>