You will be given a definition of a task first, then some input 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: Hello, I'm Thomas Miller. 
 agent: Hello, how can I serve you? 
 customer: There is an Autoexpo'2017 motorcar show which is going to be held at Las Vegas for which I wish to attend. So, please help me to book a flight. 
 agent: Sure. 
 customer: My travel dates are depart date on:10/20 and return date on:10/22. The airport codes are IL - ORD to NV - LAS. 
 agent: Ok, please wait a moment. 
 customer: I wish to travel in a flight with price limit:500 and connections limit as 1. 
 agent: Thank you for waiting there were no flight found given requirements. 
 customer: Do you need any other information? OK. Thank you, I appreciate your efforts. 
 agent: Thank you, have a nice day.
Output:
no_flight