A train goes from Shanghai to Yangzhou and passes through 4 stations on the way. How many different tickets should be prepared for this train?
一列火车从上海到扬州，中途要经过4个站，这列火车要准备多少种不同的车票．
<gadget id="calculator">5 + 4 + 3 + 2 + 1</gadget>
<output>15</output>

<result>15</result>