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 assist you? 
 customer: Helen Jackson here. Could you please help me in booking a ticket from DTW to LGA where I have a meeting to attend. 
 agent: Sure, I am here to help you. Can I have your planned travel dates please? 
 customer: My itinerary  travel dates are as follows Sept 21 and Sept 23. 
 agent: May I know your name please to proceed further? 
 customer: Already provided. 
 agent: Do you need a connecting flight? 
 customer: I would like to board a single connection flight. 
 agent: I which class do you prefer for your journey? 
 customer: I have no class preference. 
 agent: Do you have any other specifications? 
 customer: No, thank you for asking. 
 agent: Please hold on a moment. 
 customer: Sure, take your time. 
 agent: Helen Jackson, no reservation has been found on your planned travel dates. 
 customer: No issue. Thank you for your assistance. 
 agent: Thank you for approaching us.
no_flight