There are 18 children lined up in a column, and the distance between every two children is 1 meter. What is the total length of the column in meters?
有18个小朋友排成一路纵队，每两个小朋友之间相距1米，这路纵队全长大约多少米．
<gadget id="calculator">18 - 1</gadget>
<output>17</output>

<gadget id="calculator">17 * 1</gadget>
<output>17</output>

<result>17</result>