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 today? 
 customer: Can you please help me in booking flight ticket from BOS to AUS? 
 agent: Sure, I am here to help you. May I know your name please. 
 customer: I am Matthew Roberts . 
 agent: Please mention your journey dates? 
 customer: My travelling dates are 03/20 and 03/22. 
 agent: Ok, please wait a while. 
 customer: Ok, sure. 
 agent: Sorry Roberts, no flights are available on your desired route. 
 customer: Ok, fine thank you for checking. 
 agent: Thank you for reaching us.
Student:
no_flight