Instructions: 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
Input: customer: Hello. 
 agent: Hello. 
 customer: I am Angela Taylor. 
 agent: Taylor, how can I serve you now? 
 customer: I am planning to book a ticket from ATL to AOK. Ca you please help me out? 
 agent: May I know your preferred dates of trip? 
 customer: I would  like to travel on 06/19 and return back on 06/21. 
 agent: Please wait. 
 customer: Ok. 
 agent: Sorry, no flight is available. 
 customer: That's fine. Thank you for your help. 
 agent: Welcome, have a nice day.
Output:
no_flight