Is there a limit to how many "OR" conditions I can enter in PHP?

Ok so I have a block of code in WordPress that has "OR" conditions inside of the "elseif" statement. here is the code:

   <?php } elseif($index == 1 || $index == 8 || $index == 9 || $index == 16 || $index == 17 || $index == 20 || $index == 21) { ?>

So the code works great up until $index == 20 || $index == 21

Is there a limit on how many times I can use || in the elseif statement?