A shuttle bus between Hangzhou and Shanghai passes through 4 stations A, B, C and D in addition to the starting point and the ending point. If you are a conductor, please think about it, how many different tickets do you need to prepare? (You can draw a picture, maybe you will be more clear)
一辆往返于杭州和上海的班车，除起点和终点外，途径A、B、C、D这4个站点，如果你是售票员，请你想一想，需要准备多少种不同的车票？(可以画画图，也许你会更清楚)
<gadget id="calculator">5 + 4 + 3 + 2 + 1</gadget>
<output>15</output>

<gadget id="calculator">15 * 2</gadget>
<output>30</output>

<result>30</result>