Instructions: 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: Hello. 
 agent: Hello, how may I serve you today? 
 customer: I want to travel from DFW to IAH. Can you help me to book a flight ticket? 
 agent: Sure, I will help you with booking. 
 customer: Thank you. 
 agent: May I know your good name please? 
 customer: David Davis. 
 agent: Please mention your planned journey dates? 
 customer: I want to travel in the flight on Mar 07 and Mar 09. 
 agent: Do you want connecting flight for this journey? 
 customer: I am looking for a connecting flight. 
 agent: Is there any other preferences? 
 customer: I prefer to travel in business class. 
 agent: Please wait for a moment. 
 customer: Ok. 
 agent: Thank you for waiting, sorry to inform you that there is no seat available in business class in any flight. 
 customer: That's ok. Anyways, thank you. 
 agent: Thank you for visiting us, we hope see you again.
Output:
no_flight