Definition: 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. How may I aid you? 
 customer: Please book me a flight ticket from DFW to LAS to meet my family. 
 agent: Sure, I am here to help you out. May I know your travelling dates please? 
 customer: I have planned to travel on Nov 11th and return on Nov 13th. 
 agent: Can you please share your connection limit? 
 customer: I prefer connecting flight. 
 agent: Is there any other specifications? 
 customer: I want to return at evening time. 
 agent: May I know your name please? 
 customer: Margaret Rodriguez. 
 agent: Margaret Rodriguez, there are no flights available in your route. 
 customer: Ok, no problem. Thank you. 
 agent: Thank you for choosing us.
Output:
no_flight