It’s not clear at all, you don’t give its purpose or usefulness, so I don’t care.
I’ve already answered this:
http://forum.mikrotik.com/t/subtraction-of-elements-in-the-mikrotik-array-does-not-count-the-first-element-correctly/166914/3
but I still don’t see the usefulness for everyone, so if you need such a particular script with a purpose unknown to us in the forum,
I suggest you hire a consultant, if you really need it…