The school organizes a group gymnastics performance. The boys are arranged in a solid square, and a row of girls stands around the solid square. There are 72 girls participating in the performance, how many boys are there?
学校组织一次团体操表演，把男生排列成一个实心方阵，又在这个实心方阵四周站一排女生．女生有72人参加表演，男生有多少人？
<gadget id="calculator">72 / 4</gadget>
<output>18</output>

<gadget id="calculator">18 + 1</gadget>
<output>19</output>

<gadget id="calculator">19 * 19</gadget>
<output>361</output>

<gadget id="calculator">361 - 72</gadget>
<output>289</output>

<result>289</result>