Hi. I have 3 formula's which I would like merging into one?

=IF(AND(C3<$B$1,C31/1/1,D3=""),"N","")

=IF(AND(C3$B$1,D3=""),"M","")

=IF(AND(C31/1/1,D31/1/1),"Y","")

I would like all these as one formula in cell E3?

I've had a try myself but am not very good at nesting functions....

Thanks in advance.