Definition: 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
Input: customer: Hello, I am Charles Rodriguez. 
 agent: Hello, how can I aid you? 
 customer: I am planning attend my friend birthday party in Washington, can you please help me to book a flight ticket? 
 agent: Sure, could you please provide your journey details? 
 customer: My journey dates are 12/15 to 12/17. I am travelling from CO - OAK to DC - DCA. Make sure that my price limit is 5000. And I need flight with single connection. 
 agent: Please wait a moment, I will check the availability and get back to you. 
 customer: Ok. 
 agent: We are sorry to notify you that there is no flights available based in your given details. 
 customer: Ok, no issues. 
 agent: Thanks for choosing us. 
 customer: Thanks for your service. 
 agent: Have a nice day. 
 customer: Thank you.
Output:
no_flight