Among the passengers who got on at each station, exactly one passenger got off at each subsequent station.

There is a 15 stop behind the departure station, which means that 15 people get on the bus. analogize

According to the meaning of the question:

Starting station 14 people, get off 0 people.

At the second stop, 13 people get on and 1 people get off.

At the third stop 12 people get on and 2 people get off.

Get on at the fourth stop 1 1 get off at 3.

The fifth stop, get on 10 and get off at 4.

At the sixth stop, get on the No.9 bus and get off the No.5 bus.

At the seventh stop, get on the No.8 bus and get off the No.6 bus.

At the eighth stop, get on the No.7 bus and get off the No.7 bus.

Get on at the sixth stop and get off at the eighth stop.

There are fewer people getting on the bus from the ninth stop than getting off, which means that there are the most people getting on the bus after the eighth stop!

Then the seats that should be prepared should be:

14+ 13+。 . . +8+7-0- 1-2-3-4-5-6-7 = 84-28 = 56.