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. 
 agent: Hello, how may I help you? 
 customer: I am Stephanie Hall. I want to fly from LAS to DFW, please book a flight ticket with a connection. 
 agent: Sure, can I know your preferable dates? 
 customer: My travelling date are Dec 29th and 31st. 
 agent: We found  a direct flight. Shall I proceed? 
 customer: I need a lay by in between the journey. Please proceed. 
 agent: Your ticket is booked with 1012 flight number with Spirit airline and fare is 200. 
 customer: Thank you. 
 agent: Thank you for reaching us.
book