Android : android studio drawable images iteration

i put some images into the res/drawable folder. They are named (s1.png, s2.png, s3png.., 2n.png).

I want to loop (and then process) them. I would do that like:

    for (int i = 1; i < n; i++) {
        HavingFunWithPNGS(R.drawable.s + IntToStr('i'));
    }

Ofcourse thats not how it works. How does it? Thanks in advance.