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. 
 agent: Hello. How can I help you? 
 customer: Nancy Taylor here. I am a journalist, I have to interview a politician in Detroit. Could you book my ticket from PHL to DTW? 
 agent: Can you please tell your travelling dates? 
 customer: My itinerary dates are 12/11 and 12/13. 
 agent: Sorry, there are no flights available with your requested details. 
 customer: No problem, thank you so much. 
 agent: Thank you and have a nice day.
Output:
no_flight