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 am Anthony Mitchell. 
 agent: Hello, How may I help you? 
 customer: Can you help me in booking my flight ticket to Seattle SEA to visit Columbia centre? 
 agent: Sure, We are here to help you. May I know the source code? 
 customer: I will start my travel from Austin, AUS. 
 agent: Please help me with your travel dates. 
 customer: Make sure that I need a direct flight to SEA. Dates of my travel are 09/15 - 09/17. 
 agent: Please wait a minute. 
 customer: Sure. 
 agent: Sorry, No flights found with your chosen dates. 
 customer: Ok, I will look for other alternative. Thank you for assisting me. 
 agent: Thank you for availing us.
Output:
no_flight