Given the task definition and input, reply with output. 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

customer: Hi,. 
 agent: Hello, how can I assist you? 
 customer: Please provide a ticket from Minneapolis & St. Paul, MN-MSP to Oakland, CA-OAK. 
 agent: Sure, please share me your willing dates to travel. 
 customer: My travel dates are from 11/07 to 11/09. 
 agent: Ok, is there any restriction in connection? 
 customer: Please provide direct flight. 
 agent: Can I have your name please? 
 customer: My name is Alexander Roberts. 
 agent: Ok, please hold on. 
 customer: Sure. 
 agent: Sorry to inform you that there is no flight available on your dates. 
 customer: Thanks for the assistance. 
 agent: Thank you for reaching us.
no_flight