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. 
 customer: Larry Edwards here. 
 agent: Larry, how can I aid you today? 
 customer: I want to attend a Seminar in Las Vegas. Can you please help me for booking the flight ticket? 
 agent: Sure, I am here to help you. May I know your travel dates please? 
 customer: My travelling dates are 10/28 and 10/30. 
 agent: Ok, can you please provide your airport codes? 
 customer: My airport codes are SFO and LAS. 
 agent: Ok, hold on for a moment. Let me check the best flight for you. 
 customer: Ok, I will wait. 
 agent: I found a flight for you with AA airline and it costs you 200. Shall I proceed? 
 customer: Please proceed for booking the flight ticket. 
 agent: Your ticket has been booked with 1020 flight number. 
 customer: Thanks for helping me. 
 agent: Welcome, thank you for choosing us. Have a safe flight.
A:
book