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 assist you? 
 customer: will you please book me a direct flight to CLT? 
 agent: May I know your source airport code? 
 customer: I will be leaving from SEA. 
 agent: May I know your travelling dates? 
 customer: My departure is on May 4th and arrival is on May 6th. 
 agent: Is there any connection limit? 
 customer: I have already mentioned above that I need a direct flight. 
 agent: Sorry, Is there any other preferences? 
 customer: No. 
 agent: May I know your good name? 
 customer: I am Gary Taylor. 
 agent: There were no flights found with your required dates to travel. 
 customer: That's alright, thanks for your response. 
 agent: Thank you for choosing us.
Output:
no_flight