Plant trees around a square field, plant 10 trees on each side, and plant one tree at each of the four vertices. How many trees are planted around the field?
在一块正方形场地四周种树，每边都种10棵，并且四个顶点都种有一棵树．这个场地四周共种树多少棵棵．
<gadget id="calculator">10 * 4</gadget>
<output>40</output>

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

<result>36</result>