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, Benjamin Hill here. 
 agent: Hello. Hill, how can I assist you? 
 customer: I want to meet my business partner in casino, could you book my ticket from SEA to LAS? 
 agent: Please provide me your travel dates for further process. 
 customer: My trip dates are 11/29 and 12/01. 
 agent: Please wait. 
 customer: Sure. 
 agent: Sorry, no flight is available for you. 
 customer: It's ok, thank you. 
 agent: You are welcome.
no_flight