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 can I help you? 
 customer: I am Stephanie Harris. As my cultural fest was postponed, I want to change my existing reservation. Could you please help me? 
 agent: Ok Harris, I will be back with your details. 
 customer: Ok. 
 agent: No reservation found with your details. Thank you Harris, have a nice day. 
 customer: No problem, Thank you for your information.
Student:
no_reservation