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
Input: customer: Hello, I am George Roberts. 
 agent: Hello, how may I serve you today? 
 customer: I want to travel from AUS to DFW for a meeting, Can you please book a ticket for me? 
 agent: Sure, may I know your travelling days? 
 customer: My depart is on 05/27 and return is on 05/29. 
 agent: Please wait for a moment, I will check the availability of flights and inform you. 
 customer: Sure. 
 agent: Thank you for waiting. Sorry to inform you that unfortunately there are no flights available on the specified days. 
 customer: Thank You. 
 agent: Thank you for contacting us.
Output:
no_flight