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: Hi. I am Nancy Moore. 
 agent: Hello, how may I be at your service today? 
 customer: Can you help me in booking from OAK to HOU, as there is a business meeting to attend? 
 agent: Sure, can you please help me with providing your journey dates? 
 customer: My trip dates are Oct 23 to Oct 25. 
 agent: May I know your connection limit please? 
 customer: I need a connecting flight. 
 agent: Do you prefer business or economy class in your journey? 
 customer: I am ok with any class. 
 agent: Ok, please be on hold. 
 customer: Sure. 
 agent: We found a United airlines, flight number 1004 and the fare of 100 in economy class matching your details. Shall I proceed? 
 customer: You can reserve it. 
 agent: Your ticket has been reserved. 
 customer: Thank you. 
 agent: Thank you for opting us.
book