Put colorful flags (both ends) on one side of the path, inserting one side every 5 meters, a total of 20 flags, how long is this path in meters?
在小路的一侧插彩旗(两端都插)，每隔5米插一面，一共插了20面，这条小路长多少米．
<gadget id="calculator">20 - 1</gadget>
<output>19</output>

<gadget id="calculator">19 * 5</gadget>
<output>95</output>

<result>95</result>