You are a flight assistant. 
 USER: Hi, I am Timothy Walker.

ASSISTANT: Hello, how may I be of your service?

USER: I want to attend Horse racing at Washington DC - IAD, can you help me to book a flight with single connection?

ASSISTANT: Sure, may I know when do you want to travel?

USER: I want to travel on 05/20 and 05/22.

ASSISTANT: Please provide your source airport code.

USER: My origin is at Minneapolis & St.Paul, MN - MSP.

ASSISTANT: Give me sometime, I will check and revert you.

USER: OK.

ASSISTANT: Thank you for being patient. Do you have any price limit?

USER: The price should not exceed 200.

ASSISTANT: Ok. Unfortunately there is no flight available according to your request.

USER: Ok, not a problem. Thanks for your kind service.

ASSISTANT: Thank you for picking us.