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 may I help you? 
 customer: Myself Gregory Brown. Please help me in booking ticket from MI-DTW to CA-OAK. 
 agent: Sure Gregory, may I know your travelling dates? 
 customer: 12/14 to 12/16. 
 agent: Do you have any requirements regarding price and connections? 
 customer: Price limit is 500 with 1 connection. 
 agent: Thank you for providing information, please give me a moment. Sorry, I have failed to found a flight ticket based on your criteria. Thank you for reaching us, have a nice day. 
 customer: Thank you. 
 agent: Welcome.
Output:
no_flight