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: Hi. 
 agent: Hello, how can I assist you? 
 customer: Could you please check the flight availability in economy class? 
 agent: Sure, I am here to help you. Please let me know your travelling dates. 
 customer: My travelling dates are Oct 19 and Oct 21. 
 agent: Kindly mention your respective airport codes. 
 customer: My source is SEA and destination is PHX. 
 agent: Do you prefer any break in between journey? 
 customer: I need a single connecting flight. 
 agent: Are there any other specifications for you? 
 customer: I want to return in the evening. 
 agent: May I know your good name? 
 customer: I am David Moore. 
 agent: According to your information, I have found a flight with single stop over in your journey with a minimum fare of 100 with flight number 1012. Shall I proceed with this flight? 
 customer: Ok, proceed. 
 agent: Your booking is done in United Airlines. 
 customer: Thank you. 
 agent: Thank you for availing us.
A:
book