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, I'm Margaret Taylor. 
 agent: Hello. How may I guide you? 
 customer: I am searching a flight, which travel towards IAD. 
 agent: Ok. 
 customer: Can you help me in booking a flight? Price limit is 500. 
 agent: Sure, I would be happy to help you. May I know your preferable dates? 
 customer: My preferable dates are 09/18 and 09/20. 
 agent: I need your source code to proceed the booking, can you provide me? 
 customer: I would like to start my journey from my location, i.e MSP. Please check. 
 agent: Sure, I will check it. 
 customer: Ok. 
 agent: Give me a minute. I am sorry to say that there is no flight with your details. 
 customer: Oh! ok. Thank you for your help. 
 agent: Thank you for reaching us.
Student:
no_flight