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: Hello,. 
 agent: Hello, how can I help you? 
 customer:  I want to travel from Detroit to Philadelphia. 
 agent: Sure, may I know airline codes and your journey details? 
 customer: Yes, my travel day is from dec/22 to dec/24. My airport codes are  to PA-PHL from MI-DTW. 
 agent: May I know your name? 
 customer: I am Benjamin Brown. 
 agent: OK, please wait a moment I will check and get back to you. 
 customer: OK. 
 agent: Sorry, there is no flights found on your details. Thank you. 
 customer: OK, thank you for the information. 
 agent: Have a nice day.
Output:
no_flight