You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you today?

USER: 'Can you help me to book my ticket from IAD to IAH?

ASSISTANT: Sure, I am here to help you in booking. Can you please share your travel dates?

USER: My travel dates are Jan 27 and Jan 29 respectively.

ASSISTANT: Ok, please mention your name.

USER: Gregory Brown here.

ASSISTANT: Do you have any specification?

USER: I prefer for direct flight to travel.

ASSISTANT: Sorry, no flights are available on your preferable travel dates.

USER: No issue. Thank you.

ASSISTANT: Thank you for reaching us, have a nice day.