Hi there,
To compare it like @izaychik63 suggested you first need to extract second character. Using substring() function in String Manipulation node for example. Then in Rule Engine node you can have this comparison. Result can be number which you would then use in a substring() function. Or again alternative for whole logic is to use Column Expressions node 
The solution @armingrudd provided for this with regex is much better in my opinion.
Br,
Ivan