Introduction - If you have any usage issues, please Google them yourself
1) enter the route information, each flight information includes flight number, aircraft number, destination, booking number, and the total number of votes in 5.
2) booking business, each customer including name, flight number, seat number (initial 0).
3) refund business, according to the customer's flight number, refund.
4) modify flight information, when the flight information changes, you can modify the flight data file. (customer cannot modify)
Output airline information and customer information.