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. 
 customer: I am Sandra Evans. 
 agent: How can I assist you today? 
 customer: I want to change my travel dates in my previous reservation, can you please help me with that? 
 agent: Sure, please give me a moment. 
 customer: Ok. 
 agent: Thanks for waiting, there is no reservation found under your name. 
 customer: Oh! May be I am not booked my ticket properly at that time. Thank you for your service. 
 agent: Welcome, have a great day.
Output:
no_reservation