Ahh, okay... Matrixes are a pain in Excel, if possible I would look to convert to a single column.
But failing that, you would need a final column at the end, which tries to match it in each individual row. If it finds a match, it will return a number; if it can't find a match, it will return #N/A. So then your label value will be the only row that contains a number and not #N/A.
EDIT: Wait I can see where this is going. You're going to need it for 1000000000bazillion different values for "k" aren't you

. Either convert to a single column, or write a macro (fairly straightforward?).