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, myself Justin Gonzalez. 
 agent: Hello Justin, how can I assist you? 
 customer: I would like to visit Chicago to meet my brother, could you please help me in booking a ticket from ATL to ORD? 
 agent: Sure, may I know your preferred journey dates? 
 customer: My planned journey dates are 12/16 and 12/18. 
 agent: Please wait for a minute. 
 customer: Sure, take your time. 
 agent: There are no flights available at this moment. 
 customer: Ok, no problem. Thank you for your information. 
 agent: Thank you for utilising our services.
Output:
no_flight