Detailed Instructions: 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
Q: customer: Hello. 
 agent: Hello, what kind of service your looking for? 
 customer: Can you please help me with booking a flight ticket from DTW to SFO? 
 agent: Sure, please share me your travel dates. 
 customer: My travelling dates are from Sept 12-14. 
 agent: Do you need direct flight or connecting flight? 
 customer: I would be comfortable with single stop over. 
 agent: For booking, we need your good name. Please mention it. 
 customer: Justin Evans here. 
 agent: May I know your class preferences? 
 customer: I prefer business class. 
 agent: May I know your arrival and depart timings? 
 customer: I am comfortable with any time. 
 agent: We found a Frontier airline and 1001 is flight number with a fare of 700. Shall I proceed? 
 customer: You can proceed with booking. 
 agent: Your ticket is confirmed with a business class. 
 customer: Thank you for the help. 
 agent: Thank you for opting us.
A:
book