You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I aid you today?

USER: I am Frank Jackson. I am planning to visit Downtown Aquarium at Houston, could you please help me with booking a flight ticket from DCA to IAH?

ASSISTANT: Sure, I will help you with that. Can you please share your preferable journey dates?

USER: I would like to depart on June 24th and return on June 26th.

ASSISTANT: Do you have any class preference?

USER: I am comfortable with any class.

ASSISTANT: Is there any other preference?

USER: I need a direct flight.

ASSISTANT: I am sorry to say that there is no flight found under your details.

USER: That's ok, not an issue. Anyways, thank you for the information.

ASSISTANT: Thank you for reaching us.