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: Helen Miller here. 
 agent: How can I assist you? 
 customer: I would like to book a flight on the route from LAS to BOS, please help me. 
 agent: Sure Helen, can I know the travel dates please? 
 customer: I will be travelling on the dates from 12/25 to 12/27. 
 agent: Ok, wait a moment please. 
 customer: Ok, take your time and revert back to me with available information. 
 agent: There is flight in Delta airline with price 100. 
 customer: You can proceed with confirming my reservation. 
 agent: Your ticket has been booked with flight number 1019. 
 customer: Thank you for helping me out. 
 agent: Thank you for approaching us. 
 customer: Most welcome.
A:
book