In this task, you are given a conversation between a flight agent and the customer. You are given 4 options and you need to select the goal of the conversation. It is provided as part of customer's context, which has to be one of the following: `book`: Make a new reservation, `cancel`: Cancel an existing reservation, `no_flight`: No flight found for the customer's preference, `no_reservation`: No reservation / No change / No cancellation was made in the conversation, mostly enquiring details

Example input: customer: Hi. 
 agent: Hello. How can I help you? 
 customer: I would like to change my existing reservation as my plan to go for a holiday trip got postponed. Can you please help me with this? 
 agent: Sure, may I know your name please? 
 customer: My name is Anthony Phillips. 
 agent: Please wait a moment. 
 customer: Sure. 
 agent: Unfortunately there is no reservation found with your given name. 
 customer: Not a problem, thank you for checking. 
 agent: Thank you for choosing us.
Example output: no_reservation
Example explanation: Here the customer has not asked for any booking, he just wanted to update his already booked flight, so the status would be no_reservation
Q: customer: Hello, I am Lisa harris. 
 agent: Hello, How may I assist you? 
 customer: I want to attend a cultural exhibition in MA - BOS on 09/15 from IL - ORD and return on 09/17. Can you please help me out in booking a ticket with price limit of 5000? 
 agent: Sure. Give me some moment to check the availability of flight? 
 customer: OK. 
 agent: Thank you for being patience. There is a flight available based on your availability. Frontier air lines,flight number 1025. 
 customer: Can I know the price of the flight? 
 agent: Sure. The price is 100. Shall I proceed for booking? 
 customer: OK, you can proceed for booking. 
 agent: OK. Your ticket has been booked successfully. 
 customer: Thanks for your response. 
 agent: Thank you for choosing us!.
A:
book