Q: 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
customer: Hi. 
 agent: Hello. How can I help you? 
 customer: I am Richard Clark, can you please help me in booking a flight ticket from PHX to EWR? 
 agent: Sure, I will help you for booking. Can you please provide me your travelling dates? 
 customer: My trip dates are from 07/14 till 0/716. 
 agent: Ok, give me a moment. 
 customer: Ok, take your time. 
 agent: Sorry, there is no flights is available on your route. 
 customer: It's ok, thank you for checking. 
 agent: Welcome.
A:
no_flight