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: Hi. 
 agent: Hello. 
 customer: Myself Ruth Perez. 
 agent: How may I aid you? 
 customer: I want to change my existing reservation, can you help me? 
 agent: Sure, I am here to help you out. 
 customer: Thank you. 
 agent: Thank you for waiting Ruth Perez, we haven't found any reservation under your name in our database. 
 customer: That's ok, no problem. It might went wrong while booking due server issues. Any way, thank you for the information. 
 agent: Thank you for reaching us.
Output:
no_reservation