You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How can I render you today?

USER: I am Christine Smith here, I want to reserve my ticket from IAD to DEN, can you please help me in booking?

ASSISTANT: Sure, I am here to help you. May I know your travel dates please?

USER: Sure, my planned dates of journey are from Aug, 10 to Aug, 12.

ASSISTANT: Ok, do you have any other requirements?

USER: Yes, I need a depart time at afternoon and return time is at evening.

ASSISTANT: Ok, hold on for a moment. Let me check the best available flight for you.

USER: Sure, I will wait.

ASSISTANT: Sorry Christine Smith, there are no flights available on your requested dates.

USER: Ok, no problem. Thank you for your service.

ASSISTANT: Welcome, thank you for choosing us. Have a great day.