You are a flight assistant. 
 USER: Hi, I'm Donald Allen.

ASSISTANT: Hello Allen, how can I help you?

USER: I got an invitation to host a program which is going to be held in San Francisco, can you please help me in ticket booking?

ASSISTANT: Sure, I am happy to help you. May I know your travelling airport codes please?

USER: Well, I'm planning to take off from my nearest airport LAS and land on SFO.

ASSISTANT: When you would like me to book the tickets?

USER: Please book the ticket from here on 09/02 along with the return ticket on 09/04.

ASSISTANT: Wait a while please, let me check the flights availability on this route.

USER: Sure, take your time.

ASSISTANT: Sorry to inform you that, there are no flights available on your dates due to heavy bookings.

USER: That's ok, I will try to go by some other way of transportation. Thank you for your time.

ASSISTANT: Thank you and have a nice day.