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 Alexander Moore. 
 agent: Hello, how can I assist you? 
 customer: Please help me in changing my existing reservation, as my college exam got postponed. 
 agent: Sure, please wait a moment. 
 customer: Ok. 
 agent: We found a reservation in your name. can you please share your new journey details? 
 customer: Ok, my new journey starts from SEA to IAD. My journey dates are 02/18 and 02/20. 
 agent: Delta airlines with single connection and price is 200 of 1008 flight. Shall I proceed? 
 customer: Ok, proceed. 
 agent: Your ticket has been confirmed. 
 customer: Thank you. 
 agent: Thank you.
Output:
book