You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How can I assist you?

USER: Joshua Miller here. My airport codes for boarding the flight are SFO to IAD. Can you book a flight ticket?

ASSISTANT: Ok, may I know your travelling dates?

USER: My travelling dates for journey are 05/27 to 05/29. I need a connecting flight.

ASSISTANT: Sorry, no flights found on your preferable dates.

USER: Ok, not a problem. Thank you.

ASSISTANT: Most welcome.