Detailed 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
Problem:customer: Hello, myself David Baker. 
 agent: Hello. How may I help you for the day? 
 customer: I want to change my destination airport codes in my existing reservation, can you please help me out? 
 agent: Please wait a  moment, let me check with your details. 
 customer: Ok, I will wait for your response. 
 agent: Please provide me you trip details. 
 customer: My planned trip dates are 10/08 and 10/10. 
 agent: Can you please provide your airport codes which you are travelling. 
 customer: Sure, my location airport codes are PHX and DCA. 
 agent: There is a flight available with one connection and the price is 200, can I proceed with that?'. 
 customer: Fine, please reserve me a seat. 
 agent: Your ticket has been booked with the Sprint airlines and the flight number is 1002. 
 customer: Thank you for your quick service. 
 agent: Thank you for reaching us.Have a safe journey ahead.
Solution:
book