Given the task definition and input, reply with output. 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: Hello. 
 agent: Hello. How can I help you today? 
 customer: I am  Carol Williams. I want to book a fight ticket from PHX to ORD. Can you find a flight ticket for me? 
 agent: Sure, may I know your travel dates to search available flight for you? 
 customer: Sure, I am planning to travel on these days that is on 02/02 and back on 02/04. 
 agent: Wait for a minute, to check. 
 customer: Ok, make sure that the connection limit 1. 
 agent: Sorry, I could not find any flight with your connection. 
 customer: Ok, no problem. Thank you for your information. 
 agent: My pleasure.
no_flight