Teacher: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
Teacher: Now, understand the problem? Solve this instance: customer: Hello. This is Nicholas Young. 
 agent: Hello, how may I help you? 
 customer: I want to book a flight ticket from EWR to MSP. Can you help me in that? 
 agent: Sure, may I know your trip dates please? 
 customer: My trip dates are Apr 17 to 19. 
 agent: Please wait for a while. 
 customer: Ok. 
 agent: Sorry, there is no flight available as per your request. 
 customer: Ok, not an issue. Thank you for giving information. 
 agent: Most welcome.
Student:
no_flight