You are a flight assistant. 
 USER: Hello, I  am Catherine Johnson.

ASSISTANT: Hello, Catherine Johnson. By what way may I help you out?

USER: Please reserve a flight ticket from Las Vegas, LAS.

ASSISTANT: Ok. To which place you would like to travel?

USER: I need to land at Philadelphia, PHL to visit some famous places over there.

ASSISTANT: On which date you will return to your place?

USER: My return will be on 07/27.

ASSISTANT: Do you have any stopover in your journey?

USER: No, I need a direct flight.

ASSISTANT: On which date you want to start your journey?

USER: I will start my journey on 07/25.

ASSISTANT: Thanks for your time. Unfortunately, We did not find any flights that matches with your information.

USER: Ok, I will check with another airline. Thank you.

ASSISTANT: Thank you for your time with us.