Adding Column Minus Rows That Have Data In Another Column

I want a cell on one spreadsheet (SP-A) to add up a column (M) in another spreadsheet (SP-B) rows 11 through 10000.

Here's the thing, I want that cell to actually display not the sum that it gets but that sum minus all numbers (in M column again) which column E is filled out with any data for their given row...

i'm not even sure if this makes sense lol... let me use example

on SP-B there's a column M.
in row 11, value = 3
in row 12, value = 5, in this same row column E is filled with whatever
in row 13, value = 2, in this same row column E is filled with whatever
in row 14, value = 6

in my SP-A I need the cell to display 9, since rows 12 and 13 have values in E and I don't want to add those to the sum.