The ticket price for a science popularization exhibition is: ordinary tickets are 20 yuan per person, group tickets for more than 20 people (including 20 people) get a 20% discount, and the minimum number of people buy group tickets to save money.
一个科普展览会的门票价格是：普通票每人20元，团体票20人以上(含20人)按八折优惠，最少多少人时买团体票省钱．
<gadget id="calculator">16 + 1</gadget>
<output>17</output>

<result>17</result>