Detailed Instructions: 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
Problem:customer: Hello. 
 agent: Hello, how can I aid you today? 
 customer: Can you please help me to book a flight from BOS to SFO? 
 agent: Please provide your trip dates. 
 customer: Sure, I want to travel on Apr 13 and need to return on Apr 15. 
 agent: Do you need any connection limit? 
 customer: I need a flight with single connection. 
 agent: Is there any other specifications? 
 customer: My depart time must be in the evening. 
 agent: May I know your name? 
 customer: I am Virginia Parker. 
 agent: There are no flights available on your routes. 
 customer: Ok, not an issue. Thank you for checking. 
 agent: Thank you for choosing us.
Solution:
no_flight