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 help you? 
 customer: Can you please help me to change my existing reservation as I have changed my trip plan? 
 agent: Sure, I am here to help you for this. May I know your name please? 
 customer: My name is Justin Martinez. 
 agent: Please wait for a while, let me check your reservation status in our records. 
 customer: Ok. 
 agent: Sorry to intimate that, no reservation is found with your credentials. 
 customer: No problem, thank you for your information. 
 agent: Thank you very much for contacting our agency.
Output:
no_reservation