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: Hi. 
 agent: Hello. How can I help you? 
 customer: I am Eric Robinson. I want to book a ticket from PHL to ORD, can you help me? 
 agent: Sure, I will help you to book a flight ticket. Can you please share me your travelling dates? 
 customer: My travel dates are 11/06 and 11/08. 
 agent: Ok, do you have any connection limit? 
 customer: I need a connecting flight. 
 agent: Ok, may I know your arrival and departure time? 
 customer: I want to return in the afternoon. 
 agent: Sorry, no flights are available on your route. 
 customer: No problem, thanks for checking. 
 agent: Welcome, have a nice day. Thank you for choosing us.
Output:
no_flight