Twitter id gather

I need a specified amount of users that are following particular users on twitter i dont need the entire user list but if you can provide it that would be fine i need the most recent half followers down i need these users gathered in a .txt file with the user names EXACTLY LIKE THIS ex. @username1 @username2, @username3, (yes with the commas) i need the following list of @justinbieber @nickiminaj Highball me and you will be ignored, i am using a whitelisted api but i cant gather these at the moment i am using the api for something else, ANY OUTRAGEOUS QUOTES WILL BE IGNORED