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: Hi. Matthew Hill here. 
 agent: Hello, how can I assist you today? 
 customer: Can you book a flight ticket for my airport codes that is from SFO to DCA? 
 agent: Sure, On which dates would you like me to book a flight ticket for you? 
 customer: The trip dates are from 29 Oct to 31 Oct. 
 agent: Let me know your connection limit? 
 customer: I prefer a stopover flight. 
 agent: Do you have any other requirements? 
 customer: The depart time would be evening. 
 agent: Ok, please wait a moment, let me search a flight for you. 
 customer: Sure. 
 agent: Sorry to inform you, currently no flights are running at that locations due to abnormal weather conditions. 
 customer: Not a problem. 
 agent: Thank you for choosing us. 
 customer: Thank you.
Output:
no_flight