There are 20 seats in a row in the auditorium. Xiaoli and Xiaoling have to sit together, and Xiaoli sits on Xiaoling's right. How many different ways are there in the same row?
礼堂里一排有20个座位、小丽、小玲要坐在一起，并且小丽坐在小玲的右边．在同一排有多少种不同的坐法．
<gadget id="calculator">20 - 1</gadget>
<output>19</output>

<result>19</result>