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, what can I do for you today? 
 customer: My name is Karen Hill and I want to book the flight ticket from LAS to EWR. Can you please help me? 
 agent: Sure, may I know your travel dates? 
 customer: My travel dates are May 17 and May 19. 
 agent: Let me know your class preference? 
 customer: I am comfortable with any class. 
 agent: Do you have any other requirements to be met? 
 customer: I need a single connection flight. 
 agent: Sorry, no flights found on your travel dates. 
 customer: Ok, thank you for the information. 
 agent: Thank you for contacting us.
Output:
no_flight