Compare 2 columns in Excel, removing values from a 3rd and provide results in a 4th, Possibly a nested If Index/Match Formula?

Sorry that I am having to post this but my mind just cannot make sense of this today and I cannot find it in the similar questions.

I am trying to find missing SKU's based on the master list in sheets A, B, C - thus;

I have a master SKU list in a column in sheet D. I want to compare that list against SKU's in a column in sheet A and a column in sheet B. However I want to ignore any SKU if it is in sheet C. Provide the final list of results in sheet E.

For simplicity, assume the SKU is in col A for each sheet.

Sounds like a maths problem I know, but I just cannot find the switch that will ignore the values from sheet C.

I was hoping for a formula probably using IF, index and match, but I just can't get my head around it.

Any help gladly received.