A square swimming pool is surrounded by guardrails, 10 guardrails are installed on each side, and each vertex is installed. How many guardrails are installed in total?
一个正方形游泳池的四周要安装护栏，每边安装10根，每个顶点都要安装，一共要安装多少根？
<gadget id="calculator">10 * 4</gadget>
<output>40</output>

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

<result>36</result>