Excel Coulumn Header As A Field Value

Hi,

I have an excel input file with the 3 columns, named: c1, c2, c3.
I want to create an excel output file with a column name c4, whose value will one of the headers in the input file (c1, c2 or c3)
(I want it to be taken from the file, not to type it)

Is there any step that gets the column headers as values?

Thanks a lot