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 may I oblige you today? 
 customer: My name is Helen Young, I want to book a flight from TX-HOU to Denver, CO-DEN to meet my sister. Can you book a connecting flight for me? 
 agent: When you are willing to travel? 
 customer: I will fly on 11/30 and return on 12/02. 
 agent: Please wait for a moment. 
 customer: Sure. 
 agent: We found 1002 Southwest airlines with single connection with price 100. 
 customer: Please proceed with booking. 
 agent: Your, booking has been confirmed. 
 customer: Thank you for helping me with booking. 
 agent: Thank you for reaching us.
book