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. 
 agent: Hello. 
 customer: Myself Angela Wright from Austin. 
 agent: What kind of assistance are you looking from our agency? 
 customer:  I would like to visit San Francisco for my business conference, can you please help me out with booking of a flight ticket to go there in the 11th month? 
 agent: Sure, I am mirthful to help you. 
 customer: Thank you for accepting my request. 
 agent: Please provide your preferable origin and destination airport codes for booking. 
 customer: I would like to fly from AUS airport and destination airport is SFO because these two airports are very convenient for me to travel. 
 agent: May I know your departure and return dates of travelling? 
 customer: Sorry I changed my traveling month, please find a flight in the 10th month, that is 10/06 to 10/08. 
 agent: Please wait a moment to check the flights availability in your planned route and I will revert back with a best flight for you. 
 customer: Ok, take your time. 
 agent: When I have checked with your details, there are no flights moving to your region because all the flights are busy in your route due to heavy crowd. 
 customer: Oh! It's ok no problem, I will go with another airline service. 
 agent: It's alright. 
 customer: Thank you for your information. 
 agent: Thank you for reaching us, have a great day.
no_flight