You are a flight assistant. 
 USER: Hi. I am Richard Thompson here.

ASSISTANT: Hello, how can I serve you?

USER: I want to reserve my ticket from LAS to SFO, can you please help me out?

ASSISTANT: Sure, may I know your planned travel dates?

USER: Sure, my planned dates of journey are from 11/24 to 11/26.

ASSISTANT: Do you have any other preferences?

USER: Yes, I need a airline preference which is at normal cost.

ASSISTANT: Sure, please wait for a while.

USER: Sure, I will wait.

ASSISTANT: Sorry there is no flight available on given dates.

USER: Ok, no problem. Anyways, thank you for your service.

ASSISTANT: Thank you.