You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello,.

USER: I am Gary Hall.

ASSISTANT: How can I serve you?

USER: I want to book a flight ticket on 08/27 and 08/29, so can you help me with it please?

ASSISTANT: Sure, Is there any restriction on fare?

USER: No, I can pay up to 5000 for this ticket.

ASSISTANT: Can I know your boarding and landing airport codes?

USER: Yes, I would like to start from Las Vegas, NV-LAS and land at Washington, DC-DCA.

ASSISTANT: Please wait for a minute, I will let you know the flight details.

USER: Ok.

ASSISTANT: Thanks for being patience, there were no flights available with your given preferences.

USER: Ok, no problem. Thank you for the response.

ASSISTANT: Thanks for opting us.