You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you today?

USER: I am William Young. Can you book a flight ticket from PHL to IAD?

ASSISTANT: Sure, may I know your travelling dates?

USER: July, 1 and July, 3 are my travelling dates.

ASSISTANT: Do you have any other requirements?

USER: I need a connecting flight. my depart time should be at afternoon and my return time should be at evening.

ASSISTANT: Sorry, there are no flights available.

USER: That's ok, not a issue. Thank you.

ASSISTANT: Thank you for reaching us.