Here is a sample of the spreadsheet I'm working with:

Column A Column B Column C
S LS Yes
S HS No
HS NS Yes
HS HS No

I'm trying to determine a formula I can use to automatically populate Column
C with a yes or no based on the letters in columns a or b. This is just a
small sample of the letters that could be used so there are multiple
combinations (NA, NS, LS, S, HS are the letters). I was thinking I could
just use numbers instead of letters and do an if statement but letters are
preferred.

What is the best way to approach this?

Thanks in advance for your help.