Detailed Instructions: 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
Q: customer: Hello. 
 agent: Hello, how may I help you? 
 customer: Can you please help me with changing my previous booking? 
 agent: Sure, may I know your name please? 
 customer: My name is Lisa Roberts. 
 agent: Ok, please wait for a moment. 
 customer: Ok, take your time. 
 agent: Sorry, there was no reservation found with your given name. 
 customer: Oh! That's fine. Thank you for checking. 
 agent: Thank you for opting us. 
 customer: Most welcome.
A:
no_reservation