You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I aid you?

USER: I am David King.

ASSISTANT: How can I help you?

USER: I am planning to travel from SFO to DEN for a small vacation, can you help in booking a ticket?

ASSISTANT: Sure, can I know your travel dates?

USER: I prefer to travel on 06/05 and I will be back 06/07.

ASSISTANT: Give me a minute.

USER: sure.

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

USER: Than's ok. Thank you for helping me.

ASSISTANT: You are welcome.