For a square fish pond, 10 trees are planted on each side around it (all four vertices are planted), how many saplings are needed in total?
一个正方形鱼池，在它的四周每边栽树10棵(四个顶点都栽)，共需树苗多少棵？
<gadget id="calculator">10 * 4</gadget>
<output>40</output>

<gadget id="calculator">40 - 4</gadget>
<output>36</output>

<result>36</result>