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, I am Samuel Smith. 
 agent: Hello. How can I aid you today? 
 customer: I am very much Excited to visit Ellenville Fault Ice Caves in New York. EWR. Can you please help me with it? 
 agent: Sure, I am here to help you, may I know your travelling dates? 
 customer:  I want to travel on 05/11, and need to catch return flight on 05/3. 
 agent: Could you please help me with your source code? 
 customer: Source airport code is PHX. 
 agent: Sorry Samuel Smith, no flights found on your  requested travelling dates. 
 customer: Ok, no issues. 
 agent: Thank you for approaching us. 
 customer: Thanks for the help.
Output:
no_flight