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, I am Edward Williams. 
 agent: Hello Edward Williams. How can I aid you today? 
 customer: Can you please assist me in booking a flight ticket from NV-LAS to TX-AUS? 
 agent: Sure, when are you planning to travel? 
 customer: My journey dates are from 11/14 to 11/16. 
 agent: Do you need a halt? 
 customer: Yes, I need a halt in between journey. 
 agent: Thank you for your details, there are no flights found with the given details. 
 customer: That's ok, not a problem. Thanks for your information. 
 agent: Ok, thank you.
no_flight