Definition: 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
Input: customer: Hi, myself Larry Robinson. 
 agent: Hello, how can I provide assistance to you? 
 customer: Can you please book me a ticket for direct flight to reach BOS from DCA? 
 agent: May I know on which dates you are planning to start and return? 
 customer: I am planning to start my journey on Aug 25th and return on Aug 27th. 
 agent: Ok, which type of class do you prefer for your journey? 
 customer: I am comfortable with any class. 
 agent: Ok, please wait for a while. 
 customer: Sure, I'll wait. 
 agent: We are sorry to say that, there is no direct flight found on your requested dates. 
 customer: Ok, no problem. Thank you. 
 agent: Thanks for choosing us.
Output:
no_flight