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 may I help you? 
 customer: Can you please reserve me a flight ticket from IAD to DTW? 
 agent: Are you fine with connecting flight? 
 customer: Yes, I am ok with connecting flight. 
 agent: Sure, can you please specify me your dates of travel? 
 customer: Sure, my travel dates are from May 16 to May 18. 
 agent: May I know your specifications? 
 customer: No more specifications. 
 agent: Let me know your name? 
 customer: Myself Ruth Nelson. 
 agent: Sorry to say, no flight is available for you. 
 customer: That's ok, no problem. Thank you for the information. 
 agent: Thank you for reaching us.
Output:
no_flight