You will be given a definition of a task first, then some input 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: Hello. 
 agent: Hello, how can I aid you today? 
 customer: Could you please book me a plane ticket from AUS to HOU? 
 agent: Sure, your travel dates please? 
 customer: I will leave on May 17 and return on May 19. 
 agent: Is there any class preference? 
 customer: Yes, I would prefer to travel in an economy class. 
 agent: Any other requirement to be met? 
 customer: Yes, I need a lay by. 
 agent: Can you mention your name to proceed further? 
 customer: I am Jack Harris. 
 agent: American Airlines has a connecting flight with number 1022 for fare 100, shall I proceed? 
 customer: Perfect, please proceed. 
 agent: Your ticket is reserved in economy class. 
 customer: Thanks for your service. 
 agent: Thank you for opting us.
Output:
book