Given the task definition and input, reply with output. 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 can I aid you today? 
 customer: Can you please help me with booking a flight ticket from IAD to DEN? 
 agent: Sure, can you please share your travelling dates? 
 customer: My travelling dates are from July 31 to Aug 02. 
 agent: Do you have class preference? 
 customer: I am comfortable with any class. 
 agent: May I know your name? 
 customer: Ronald White here. 
 agent: We found American Airline with fare 200 and flight number is 1023 with connecting flight. Shall I proceed with the booking? 
 customer: You can proceed with booking. 
 agent: Your booking is done. 
 customer: Thank you for the help. 
 agent: Thank you for choosing us.
book