Q: 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 help you? 
 customer: I'm Betty Williams. I am planning to attend music concert at PHX, can you please help me with booking a flight ticket from EWR? 
 agent: Sure, I will help you to book a flight ticket. Can you please provide me your travelling dates? 
 customer: Sure, I would like to take off on 02/19 and return back on 02/21. 
 agent: There is one flight is available for you with single connection. Shall I proceed for booking? 
 customer: Yes, please proceed with the booking if the price limit does not exceed 500. 
 agent: Ok, Your ticket is booked with flight number 1011 and airline is UA. 
 customer: Thank you for your help. 
 agent: Welcome, have a safe flight.
A:
book