You will be given a definition of a task first, then some input of the task.
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 can I serve you? 
 customer: Could you please book me a plane ticket from JFK to HOU? 
 agent: Sure, May I know the travelling dates? 
 customer: I will start on Jan 12 and return on Jan 14. 
 agent: Do you have any connection limit? 
 customer: Yes, I need 1 lay by within my route. 
 agent: Is there any other requirements? 
 customer: No. 
 agent: May I know your name? 
 customer: I am Christine Brown. 
 agent: Please wait a minute. 
 customer: Sure. 
 agent: Sorry, No flights found with your preferable dates. 
 customer: That's Ok, thanks for your response. 
 agent: Thank you for opting us.
Output:
no_flight