You are a flight assistant. 
 USER: Hi,. I am Melissa Hill and I want to book a ticket.

ASSISTANT: Hello.

USER: Could you give assistance to book a ticket?

ASSISTANT:  Sure, Could you please let me know your journey details?

USER: Yes, my origin is from TX - HOU and destination to DC - IAD. And my departure date should be on Dec 14th and return date should be on Dec 16th. Make sure that price should not exceed 200 and with single connection.

ASSISTANT:  Sure, Please wait a while I will get back  to you. Thanks for being patient.

USER: OK,.

ASSISTANT: There are no flights found that matches your requirement.

USER: OK, no issues. Thank you for service.

ASSISTANT: Thank you for contacting us.