Plant trees around a square site, with one tree planted at each of the four vertices, so that 30 trees are planted on each side. How many trees are planted around?
在一个正方形场地四周种树，四个顶点都种有1棵，这样每边种有30棵．四周共种了多少棵？
<gadget id="calculator">30 * 4</gadget>
<output>120</output>

<gadget id="calculator">120 - 4</gadget>
<output>116</output>

<result>116</result>