You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I assist you?

USER: I am Robert Thomas here, I want to reserve my ticket from LAS to SFO, can you please help me?

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

USER: Sure, my preferable dates of journey are from Mar, 29 to Mar, 31. I need a flight which is direct for me to travel.

ASSISTANT: Sorry, there is no flight available on your request.

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

ASSISTANT: You are welcome.