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: Hi. 
 agent: Hello, how may I help you? 
 customer: Please help me in booking flight ticket from LAS to SFO to attend meeting. 
 agent: Sure, may I know your name? 
 customer: Linda Williams here. 
 agent: When do you want to travel? 
 customer: My trip dates are Sept 21 to Sept 23. 
 agent: May I know your connection limit? 
 customer: I need a direct flight. 
 agent: Do you have any other preferences? 
 customer: No. 
 agent: Sorry, there are no flights available on your request. 
 customer: Ok, no problem. Thank you. 
 agent: Thank you for choosing us.
Student:
no_flight