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: Hi. 
 agent: Hello. How can I aid you today? 
 customer: I am Richard Williams here, I want to reserve my ticket from HOU to ORD, can you please help me out? 
 agent: Ok, may I know your travelling dates? 
 customer: Sure, my willing to travel dates are from Oct, 17 to Oct, 19. 
 agent: Can you please mention your depart and arrival timings? 
 customer: Yes, I need a return time at morning. 
 agent: May I know your connection limit? 
 customer: Yes, I need a direct flight. 
 agent: Ok, please wait for a while. 
 customer: Sure, I will wait. 
 agent: Sorry, no flights found on your route to reserve your ticket. 
 customer: Ok, no problem. Thank you for your service. 
 agent: Thank you for connecting with us.
Output:
no_flight