The following cells are only important to me: A1, B5, J20 and M6

I would like to use the above four cells with the Excel countif()
function as follows, but this does NOT work:

countif (A1,B5,J20,M6, 0) ' Does NOT work!

This does not work because countif() only accepts 2 parameters,
a range and a criteria.

How can I make this work?? I already tried the following:

countif(Range(A1,B5,J20,M6), 0 )

but that didn't seem to work either.

Please let me know what I'm missing.

thankx