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 can I assist you? 
 customer: My plans to visit Washington Entrepreneur summit has been postponed, I would like to change my existing reservation. 
 agent: May I know your name? 
 customer: My name is Mary Carter. 
 agent: Sorry, there is no reservation found. 
 customer: Ok, no issues. 
 agent: Thank you. 
 customer: Thank you for your help.
Output:
no_reservation