Filtering excel data based on criteria of interest

Hi all,

I'm really new in this field so, to be able to explain my problem, I attached a short example sample for you. I would be highly appreciated if please take a look at it and help me out to get what I want.

I want : if N shorter than (M+200), keep M
if D=N and (M+200) < N, discard M and keep N

Thank you very much in advance.