Next Item in Line Formula

I am creating an approval flow in Ninox. 

I have a field named 'Current Step' and a list of that displays the order of the steps. Named 'Step Order' and the value is '1,2,30'

I want a formula that displays what the next step is by looking at 'Current Step'

For example, if 'Current Step' is 2, the next Step should display as 30.

How do I achieve this?

Thank you,

S Moore