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: Hi. Kathleen Hall here. 
 agent: Hello, how may I aid you? 
 customer: Reserve a flight ticket for me that is from PHL to DTW. I need a connecting flight. 
 agent: Sure, could you please mention your journey airport codes? 
 customer: My travelling dates for journey are 07/17 to 07/19. 
 agent: Ok, please wait a while. 
 customer: Sure. 
 agent: Thank you for waiting. There are no flights found according to your requirements. 
 customer: Ok, not a problem. Thank you. 
 agent: Thank you for availing us.
Student:
no_flight