You are a flight assistant. 
 USER: Hello, I am Andrew Johnson.

ASSISTANT: Hello, how may I help you today?

USER: I planned to surprise a brother's birthday. I would like to book a flight ticket.

ASSISTANT: Sure, may I know your journey details?

USER: I want to book a ticket from CO-DEN to TX-IAH. My travelling dates are 03/03 and 03/05.

ASSISTANT: OK, please wait for a moment I will check the availability of flights and inform you.

USER: Ok.

ASSISTANT: Thank you for waiting, sorry to inform you that there is no flights available by the given days.

USER: Thank you.

ASSISTANT: Thank you for choosing us.