You will be given a definition of a task first, then an example. Follow the example to solve a new instance of the task.
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

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.
Solution: no_reservation
Why? 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

New input: customer: Hi, Rachel Evans here. 
 agent: Hello, how can I aid you today? 
 customer: I want to go Brooklyn walking tour on 06/05, can you book me a flight ticket with price under 500. 
 agent: Sure, may I know your return date? 
 customer: Sure, it's 06/07. 
 agent: Let me know your airport codes. 
 customer: I would like to fly from NC-CLT to NY-LGA. 
 agent: Do you have any connection limit. 
 customer: Yes, I need a single connecting flight. 
 agent: Thanks for waiting, there is a flight with airline: UA, flight number: 1003, price 100, 1 connection. Shall I proceed? 
 customer: Please proceed. 
 agent: Your ticket has been confirmed. 
 customer: Thank you for your assistance. 
 agent: Thank you.
Solution:
book