Date stamp when cell changes for a number of rows.

Hi All,

I have a problem that has been nearly answered on a number of threads, just with a slight subtle difference.

I want to add a date stamp above a cell when the value in that cell changes, this will be for a number of alternate rows. For example.

Row 1: Date 1 Date 2 Date 3
Row 2: Change 1 Change 2 Change 3
Row 3: Date x Date y Date z
Row 4: Change x Change y Change z

(dates appear in rows 1 and 3 when a change is made in 2 /4)

This is to be done for around 600 rows. I have found this VBA code that seems to be along the rite lines but dont know how to apply it to a large number of alternating rows.

If Not Intersect(Target, Range("a:a")) Is Nothing Then
    Target.Offset(0, 1) = Date
End If
End Sub

Any help would be great!