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. 
 agent: Hello, how can I aid you today? 
 customer: Could you please help me to book a flight ticket from DEN to PHX? 
 agent: Please provide your journey dates. 
 customer: My journey dates are Apr 03 and Apr 05. 
 agent: Do you need any connection limit? 
 customer: I need a direct flight. 
 agent: Do you have any other specifications? 
 customer: No. 
 agent: May I know your name? 
 customer: I am Joseph Gonzalez. 
 agent: There are no flights available on your routes. 
 customer: Not a problem, thank you for the information. 
 agent: Thank you for opting us.
Student:
no_flight