HI , and a good day to all programmers

I need a UDF , which to count non blank cells
above the cell which contain this UDF . When
the UDF find the first non blank cell , to stop
the count .

Example :

A1 - nonblank
A2 - blank
A3 - blank
A4 - blank
A5 - UDF

here , the result of UDF from cell A5 must be 3 .
I need to count only above in the column , not in the
left or right .

Thank you