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? 
 customer: My name is Benjamin Miller, I want to book a flight to visit my uncle's house with my family. Can you book a connecting flight for me? 
 agent: Sure, Please help me with your travel dates. 
 customer: I will fly on 05/07 and return on 05/09. 
 agent: May I know the journey codes? 
 customer: My source airport is CO-DEN and my destination is NY-LGA. 
 agent: Please wait a minute. 
 customer: Sure. 
 agent: Sorry, No flights found with your preferable dates. 
 customer: Thank you for the information. 
 agent: Thank you for opting us.

no_flight