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, how may I assist you? 
 customer: I am Donald Garcia. My business meeting is postponed, so I need your help me to change my existing recent reservation, can you help me? 
 agent: Donald, please wait for a moment. 
 customer: Ok. 
 agent: I am sorry Donald, there is no reservation with your details. 
 customer: Thank you for your service. 
 agent: Thank you for contacting us.
Output:
no_reservation