Q: 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
customer: Hello. 
 agent: Hello, how may I aid you? 
 customer: I am planning to travel from BOS to SEA. Can you please help me to book a ticket? 
 agent: Ok, which class do you prefer to travel? 
 customer: I would prefer economy class. 
 agent: May I know your travelling dates to search for the flight? 
 customer: My travelling dates will be on Sept 17 to Sept 19. 
 agent: May I know your connection limit? 
 customer: I need a direct flight. 
 agent: Can I have your name? 
 customer: George Perez here. 
 agent: Sorry to say, there is no flight available for you. 
 customer: Ok, not an issue. 
 agent: Thank you for reaching us. 
 customer: Thank you.
A:
no_flight