Given the task definition and input, reply with output. 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 assist you now? 
 customer: I want to book a ticket from DEN to IAD to attend seminar, can you help me in booking? 
 agent: sure, I am happy to help you with that. Can I have your travel dates please? 
 customer: I am departing on Mar 10 and return on Mar 12. 
 agent: Ok, please let me know the timings of your journey. 
 customer: I do not have any time preferences. 
 agent: Do you prefer any specific class to travel? 
 customer: I do not have any class preference. 
 agent: Are you looking for any connecting flight or direct flight only you want? 
 customer: I prefer a connecting flight. 
 agent: Can I have your good name please? 
 customer: My name is Matthew Campbell. 
 agent: Ok, please wait a moment. 
 customer: Sure. 
 agent: UA airlines running a direct flight in your route which can provide a ticket with fare 200  in economy class. Are you ok with this flight? 
 customer: Please proceed for booking. 
 agent: Ok Matthew Campbell, your ticket booking has done and the flight number is 1001. 
 customer: Thank you for your help. 
 agent: Thank you for choosing us, have a great journey.
book