Teacher: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
Teacher: Now, understand the problem? Solve this instance: customer: Hello. 
 agent: Hello. How may I aid you? 
 customer: Can you please help me to change my existing reservation? 
 agent: Sure, I am here to help you. 
 customer: Thank you. 
 agent: May I know your name please? 
 customer: Amanda Phillips. 
 agent: Sorry to inform you that there is no active reservation on your given name. 
 customer: Ok, no problem. Thank you for checking. 
 agent: Thanks for contacting us.
Student:
no_reservation