Detailed 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
Problem:customer: Hello. 
 agent: Hello. How can I assist you today? 
 customer: I am Robert Campbell, please reserve my ticket from BOS to DTW? 
 agent: Sure, can you please share your trip dates? 
 customer: My trip dates are 07/21 and 07/23. 
 agent: Sorry, no flights are available on you route. 
 customer: Ok, please proceed. Thank you for your help. 
 agent: Welcome.
Solution:
no_flight