The second-grade children of Zhenhai Yale School planted trees on the side of a path. The children planted a tree every 2 meters (trees were planted at both ends of the road), and finally found that a total of 11 trees were planted. How long is the path in meters?
镇海雅乐学校二年级的小朋友到一条小路的一边植树．小朋友们每隔2米种一棵树(马路两头都种了树)，最后发现一共种了11棵，这条小路长多少米．
<gadget id="calculator">11 - 1</gadget>
<output>10</output>

<gadget id="calculator">10 * 2</gadget>
<output>20</output>

<result>20</result>