Definition: 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
Input: customer: Hello. 
 agent: Hello, how may I guide you? 
 customer: Myself Gary Clark. 
 agent: Ok. 
 customer: I need to travel Charlotte, can you please reserve flight ticket from DFW and CLT? 
 agent: Sure, can I know your preferable dates? 
 customer: My travelling dates are Feb,07 and Feb,09. 
 agent: I am sorry, there are no flights available. 
 customer: That's ok, thank you for searching flights. 
 agent: Thank you, have a good day.
Output:
no_flight