18 little white rabbits stand in a row, and there is a mushroom between every two little white rabbits. How many mushrooms are there in total?
18只小白兔站成一排，每两只小白兔中间有一个蘑菇，一共有多少个蘑菇．
<gadget id="calculator">18 - 1</gadget>
<output>17</output>

<result>17</result>