Teacher: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
Teacher: Now, understand the problem? Solve this instance: customer: Hello. 
 agent: Hello, how can I help you today? 
 customer: I want to book a flight ticket from Charlotte CLT to PHL. Can you find a flight ticket for me? 
 agent: Sure, can you please share your journey dates that you prefer to travel? 
 customer: Ok, my planned trip dates are on Aug 18 and return on Aug 20. 
 agent:  Do you require any stopovers in your journey? 
 customer: I need a direct flight to travel. 
 agent:  Would you let us know if you have any other preferences? 
 customer: No, I don't have any other specifications. 
 agent: Please share your name. 
 customer: Sure. I am Joseph Hall. 
 agent: Sorry to say, no flights found with your requirement. 
 customer: Ok, not an issue. 
 agent: Thanks for reaching us. 
 customer: Thank you for your help.
Student:
no_flight