Q: 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 Wright. 
 agent: Hello, how can I help you today? 
 customer: I have a plan to visit my brother's house at Oakland, please book a flight ticket under price 500. 
 agent: Sure, we are here to help you. 
 customer: Thank you. 
 agent: Kindly mention your travel dates. 
 customer: My travelling dates are from 01/27 to 01/29. 
 agent: Could you please help me with your airport codes? 
 customer: I want to fly from LAS to OAK. 
 agent: Ok, please wait a moment. 
 customer: Ok. 
 agent: Sorry to inform, no flights found with your requirement. 
 customer: No problem, thank you. 
 agent: Thanks for reaching us.
A:
no_flight