Code to run automatically

hi there,

I have a folder named "A". Inside this folder are 10 workbooks, named 1 through to 10. The workbooks contain the same amount of sheets and all tables are the same. Only the values differ. (naturally). There is another workbook which is named "master", also within this same folder "A". I am looking for a code that I can put in the "Master workbook, sheet 1", which will sum, lets say all the "A1" cells of all the "sheet 3" sheets of the 10 workbooks, BUT, the code should run automatically when workbook 11 is added to this "Folder A", and recalculate all the "A1" cells. Anytime a workbook is added, the code must automatically run and re-calculate. Is this at all possible?. I am using excel 2013.. any help will be greatly appreciated and I'm thanking you guys in advance already...