There are 19 bus stations from Chengdu to Chongqing (including Chengdu and Chongqing). How many kinds of bus tickets should be prepared?
成都到重庆共有19个客车站(包括成都、重庆在内)，要准备多少种客车票．
<gadget id="calculator">2 * 171</gadget>
<output>342</output>

<result>342</result>