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 Paul Collins. 
 agent: Hello, How exactly I can serve you the best today? 
 customer: I want to book a flight ticket from Austin to San Francisco, so can you please book me a direct flight? 
 agent: Sure, we are rapturous to help you. 
 customer: Thank you. 
 agent: Could you please help me with providing your corresponding airport codes? 
 customer: Yes, my airport codes are TX-AUS and CA-SFO. 
 agent: On which dates would you like me to book a flight ticket for you? 
 customer: I want to book a flight ticket on dates 12/18 and 12/20. 
 agent: Ok, please wait a moment, let me search a flight for you. 
 customer: Ok. 
 agent: Sorry, there were no flights with your information due to having some bad weather conditions. 
 customer: That's ok. Thank you for the response. 
 agent: Thank you for choosing us, hope to serve you better next time.
A:
no_flight