index/match "closest to X (value)"?

Hi all
So I have 4 columns, named "Type", "IV" "Delta" and "Counter". (you'll note that all "p" Type Deltas are negative and all "c" Deltas are positive).
I need a formula to find me the IV of the "p" with the Delta value closest to 0.25 and subtract it from the the IV of the "c" with the Delta value closest to 0.25.

To complicate things, the file is extremely big and the data is split into sets or "blocks" by the "Counter" column (D). so for all rows of block 1 D=1, for all rows of block 2 D=2 etc...

so to break it down I need to:
For each "Block" (ie, unique D value)
1. find the IV value(B:B) for which A="c" AND for which ABS(0.25-ABS(C)) is zero or closest to zero.
2. find the parallel with A="p"
3. Subtract IV of "p" from IV of "c".

forum delta.xlsx


many many thanks..