Modifying the result of an IFs formula based on whether another cell is filled.

Hello. Right now I'm using the following simple formula.

=IFs(S20="X",-3,O20="X",-2,L20="X",-1,H20="X",0,H20="",0)

And I'm trying to add a condition where if another box is filled with an X, it takes the result if the IFs statement and subtracts an addition -1.

Any advice on how to do this?