Given the task definition, example input & output, solve the new input case.
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
Example: customer: Hi. 
 agent: Hello. How can I help you? 
 customer: I would like to change my existing reservation as my plan to go for a holiday trip got postponed. Can you please help me with this? 
 agent: Sure, may I know your name please? 
 customer: My name is Anthony Phillips. 
 agent: Please wait a moment. 
 customer: Sure. 
 agent: Unfortunately there is no reservation found with your given name. 
 customer: Not a problem, thank you for checking. 
 agent: Thank you for choosing us.
Output: no_reservation
Here the customer has not asked for any booking, he just wanted to update his already booked flight, so the status would be no_reservation

New input case for you: customer: Hello. 
 agent: Hello. How can I aid you at this moment? 
 customer: Deborah Robinson here. I would like to visit Philadelphia for business meeting in the month of September, can you please help me out with booking of a flight ticket to go there? 
 agent: Sure, I will assist you with that. Can you please mention your preferable airport code names for booking flight ticket? 
 customer: Sure, I will prefer EWR and PHL as my origin and destination airport codes for booking. 
 agent: May I know your trip dates for further process? 
 customer: I am planning to leave on 09/19 and please book my return ticket on 09/21. 
 agent: Thank you for providing your travel details. I will put the conversation on hold to check the best flights available in your route. 
 customer: Ok, take your time. 
 agent: According to your information, I have found a flight with single stop over in your journey with a minimum fare of 200 is provided by Hawaiian airlines. Shall I proceed with this? 
 customer: That's fine for me, you can proceed with booking. 
 agent: Your flight ticket is booked successfully, flight number is 1002. 
 customer: Thank you for your kind assistance in booking of my ticket, have a nice day. 
 agent: Thank you for choosing us, have a nice day.
Output:
book