A road is 100 meters long, and a tree is planted every 5 meters on both sides of the road. The starting point and the ending point are stop signs, and no trees are planted. How many trees can be planted in total?
一条路长100米，在路的两边每隔5米栽1棵树，起点和终点是站牌，不用栽树．一共可以栽多少棵树？
<gadget id="calculator">100 / 5</gadget>
<output>20</output>

<gadget id="calculator">20 - 1</gadget>
<output>19</output>

<gadget id="calculator">19 * 2</gadget>
<output>38</output>

<result>38</result>