Get every 2nd character of a string

Hi,

Do you know what's CF function do I need to get every 2nd character of a string?  Basically, I have a string: w3f587j8a9.  I want to get every 2nd, 4th, 6th, 8th, 10th, ect...  So the result would be 35789.  Of course the limit of the loop will be like 4 characters or something like that.

Thanks.