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. 
 agent: Hello. How may I assist you today? 
 customer: I am Sarah Mitchell. 
 agent: Welcome to flight booking agency Sarah. 
 customer:  Due to sudden change in my planned dates of journey, I would like to change my reservation. Can you please help me out with changing of my reservation? 
 agent: Sure, I will help you with that. 
 customer: Sure. 
 agent: I have found your reservation. Can you please provide your preferable airport codes? 
 customer: Sure, my travel airport codes are from SFO to IAH. 
 agent: Ok, may I know your planned dates of travelling? 
 customer: My travel dates are 03/25 and return back on 03/27. 
 agent: Please wait a moment to check the flights. 
 customer: Ok, take your time. 
 agent: We regret to tell you there are no flights moving to your region with you planned dates of travelling. 
 customer: No issues with that one. Thank you for your immediate response. 
 agent: Thank you for reaching us, have a great day. 
 customer: Welcome.
Output:
no_flight