Page numbers in the inner gutter on file with pages dropping in and out.

I need a rule that will count the pages in a file, and return the page number if the page is an odd numbered, and a different rule in another box on the other side of the page that returns the page number if it is even.

The file has muliple pdf's of multiple page length that are swappin in and out, so there is not a way to control if it should be an odd or even page through the overflow, as they do not want blank pages in the book.

if (pagenumber % 2== 0)

return pageNumber;

else return "";

something like this is my idea, but i don't know how to define the pagenumber variable.

any help is greatly appreciated.

thanks

var pagenumber = CreateResource("YourFileName.pdf").countPages;