You will be given a definition of a task first, then an example. Follow the example to solve a new instance of the task.
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: 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.
Solution: no_reservation
Why? 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: customer: Hello. I am Helen Hall. 
 agent: Hello, how can I assist you today? 
 customer: Can you help me booking a flight ticket from DCA to LAS? 
 agent: Sure, I am glad to help you. 
 customer: Thank you. 
 agent: May I know your journey dates please? 
 customer: I will start on 03/24 and return on 03/26. 
 agent: Ok, please share your specifications. 
 customer: I need a break in my journey. 
 agent: Thanks for your details, please wait. 
 customer: Sure. 
 agent: Thank you for waiting, we found a connecting flight with a fare of 100 in 1019 Hawaiian airline. 
 customer: Please proceed with the booking. 
 agent: Ok, your ticket has been confirmed. 
 customer: Thank you for your kind service. 
 agent: Thank you for opting us.
Solution:
book