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 assist you? 
 customer: Please help me to book a flight ticket from IAD to ATL. 
 agent: Sure, we are happy to help you. May I know your travelling dates? 
 customer: My journey dates are Mar, 5 and Mar, 7. 
 agent: Do you prefer any break in between journey? 
 customer: Yes, I need a break. 
 agent: Are there any other specifications for you? 
 customer: I need to depart at afternoon time. 
 agent: May I know your good name? 
 customer: Michael Carter here. 
 agent:  Sorry, no flights are available on your journey routes. 
 customer: Not a problem, thank you for the information. 
 agent: Thank you for choosing us.
Output:
no_flight