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, I am Michael Green. 
 agent: Hello, how may  I help you today? 
 customer: I want to book a ticket. 
 agent: OK, Please tell me your journey details. 
 customer: I want to travel from Denver, CO - DEN to San Francisco, CA - SFO. 
 agent: May, I know your date of journey? 
 customer: My journey dates is 08/28 to 08/30. My price limit is 5000. I need a single connections. 
 agent: OK,  Please wait a minute. 
 customer: Sure. 
 agent: Thanks a lot for being patience. 
 customer: OK. 
 agent: Your  airline :Frontier, flight number:1003, price :200, connection limit :1. 
 customer: OK. Thanks for the information.
Output:
book