Compare Adjacent Cell In Excel excluding if the cell is blank

Hi Guys

I am trying to compare the adjacent cells , if the cells are blank skip the cells go to another one.
if all the cells have the same value then it should type as "N", if any of the cells has different value then it should be Y.
Cell1=Empty, Cell2 = Empty, Cell3 = 4:00:00, Cell4=4:00:00  then it should be "N"
Cell1=1:00:00, Cell2 = Empty, Cell3 = 5:00:00, Cell4=3:00:00  then it should be "Y"
Compare-Adjacent-Cells.xls