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. I am Amanda Walker. 
 agent: Hello, What kind of help are you expecting from our side? 
 customer: Please book me a ticket from PHL to HOU to meet my old friends. 
 agent: Sure, Can you please let me know your travelling dates? 
 customer: I have planned to travel on 07/15 and 07/17. 
 agent: Ok, which type of class do you prefer for your journey? 
 customer: I am ok with any class. 
 agent: Do you need any whistle stop in between your journey? 
 customer: I need a halt. 
 agent: Ok, please wait a moment. let me search a flight for you. 
 customer: Ok, I will wait. 
 agent: We have found a connected flight with Frontier airlines, flight number 1000 and the fare of 100. Shall I proceed for booking? 
 customer: Ok, please book this ticket. 
 agent: Your ticket has been reserved. 
 customer: Thank you. 
 agent: My pleasure, I hope you will enjoy this airline.
book