You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I aid you?

USER: I am planning to visit Houston to meet my uncle, can you please book me a ticket from DCA to HOU?

ASSISTANT: Sure, can you share your trip dates?

USER: My planned dates of journey are from Feb 18 to Feb 20.

ASSISTANT: Do you have any preferences?

USER: I need a ticket in economy class for this trip.

ASSISTANT: May I know your name?

USER: My name is Kathleen Clark.

ASSISTANT: Sorry, there is no economy class available on your given dates.

USER: Ok, not an issue. I will find any alternate for this trip.

ASSISTANT: Thank you for reaching us.

USER: Anyways, thank you for providing information.