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, I am Raymond Allen. 
 agent: Good morning Allen, how may I help you? 
 customer: I need to attend my sisters wedding at Charlotte, NC-CLT on 03/31, so could you help me with the booking? 
 agent: Sure, could you please provide your source city? 
 customer: Source city will be San Francisco, CA-SFO. 
 agent: OK, can you please provide your travel dates? 
 customer: Yes, my travelling dates are from 03/31 to 04/02. 
 agent: OK, please wait a moment. 
 customer: Sure. 
 agent: Sorry, no flights found on your dates. 
 customer: Thank you for your information. 
 agent: Thank you.
Output:
no_flight