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 may I serve you for the day? 
 customer: Can you please help me in booking a flight ticket from SFO to DEN? 
 agent: Sure, may I know on which dates you wish to travel? 
 customer: I wish to start my journey on Dec 23rd and return on Dec 25th. 
 agent: May I know your name please? 
 customer: I am Timothy Williams. 
 agent: Is there any airline preference in your journey? 
 customer: No. 
 agent: Please let me know your connection limit. 
 customer: I want a single connection in between my journey. 
 agent: Do you have any more specifications in your journey? 
 customer: I want to depart in the afternoon. 
 agent: Sorry, there are no flights are available on your preferred routes, due to bad weather conditions. 
 customer: Ok, no issues. Thank you. 
 agent: Thank you for choosing us.
no_flight