Given the task definition and input, reply with output. 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: Hello, I am Charles Hall. 
 agent: Hello, how can I support you today? 
 customer: I want to attend sports festival with my coach in Austin, can you help me with single connection of flight? 
 agent: Sure. Let me know your travelling dates. 
 customer: My depart is on 12/04 and return on 12/06. 
 agent: May I know your airport codes? 
 customer: My origin is IAD and destination is AUS. 
 agent: Please wait for a moment. 
 customer: OK. 
 agent: There is a flight with airline: Spirit, flight number:1002, price 200, 1 connection. Shall I proceed? 
 customer: OK, proceed with booking. 
 agent: Your ticket has been confirmed. 
 customer: Thank you for the help. 
 agent: Thank you, have a nice day.
book