Support with ISBLANK and IF statements

I'm looking to return a value based on the latest of a range of cells having a result.

I log data at fixed points and want to be able to display the latest value listed. I've tried using If and ISBLANK but don't seem to be able to find the best combination that works.

Currently looking at this set up:

Display latest grade in K3. Information should be taken from cells S3, W3 and AA3 in that order. Ie. If there is data in S3 only then display that result in K3. If there is data in W3 then display the data from W3 in K3, and if there is data in AA3 then display that data in K3.

Thanks in advance!