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It's not possible within the UI unless you would try to apply various string-functions within multiple nested if-loops. Even with just those few values from your example it would need quite a lot of efforts.
Much better would be to split these concat-string within the load per subfield() maybe within an extra table which just contains the concat-string as KEY and the splitted values from them. Then just a max(SplittedValues) would be enough.
If you're trying to do this in front end, you can use =RangeMax($(=concatfield)) in a text object (for example) to find the max. Even if that's the case, however, I suggest you follow @marcus_sommer 's advice and do it in back end instead.
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