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 aid you? 
 customer: Can you help me to book a flight ticket from LAX to DEN? 
 agent: Sure, We are here to help you. Can I know your travelling dates? 
 customer: Ok, please can you help me to book a ticket for the dates May 1st and May 3rd respectively? 
 agent: Do you need any break? 
 customer: Ok, please can you book a connecting flight? 
 agent:  Is there any other requirements for this trip to met with, so that I can find a suitable flight for your journey? 
 customer: Ok, please check flight which depart during afternoon. 
 agent: May I know your name? 
 customer: My name is Emily Taylor. 
 agent: Please be on hold for sometime, as I can check a flight for your journey with the best airlines. 
 customer: Ok, I will wait for your response. 
 agent:  We are unable to provide flight in between your journey routes due to some technical up-gradation at destination airport. 
 customer: That is ok, thank you for assisting me. 
 agent: Thank you for reaching us.
no_flight