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
Input: customer: Hello. 
 agent: Hello. How may I help you today? 
 customer: My holiday vacation has been postponed, can you please help me for changing the existing reservation? 
 agent: I will help you with that. 
 customer: Thank you. 
 agent: Please wait for a moment. May I know your name please? 
 customer: Sure, please check the reservation is on the name of Richard Evans. 
 agent: I am sorry to say that there is no reservation found. 
 customer: Ok, no problem. Thank you for your information. 
 agent: Thank you for contacting us.
Output:
no_reservation