Between Ningbo and Hangzhou, the train has to stop at 7 stations, and the fares between the two stations are different. So how many different fares are there from Ningbo to Hangzhou?
宁波到杭州之间，火车中途还要停靠7个车站，相互两站间的票价都不一样．那么宁波到杭州共有多少种不同的票价．
<gadget id="calculator">2 - 1</gadget>
<output>1</output>

<gadget id="calculator">7 + 1</gadget>
<output>8</output>

<gadget id="calculator">8 + 7 + 6 + 5 + 4 + 3 + 2 + 1</gadget>
<output>36</output>

<result>36</result>