compare 2 different numbers and copy the last 3 digits.

Hi can someone help me with this:
It's difficult to explain so I will just give an example with what I need as end result:
A
123456
987123
456963

B
123965
987582
456123


I need in C
123456-965
987123-582
456123-963 (hier you see I began with the number in B than the 3 digits from A because the number 456123 < than the 456963 in A)

in the attachement I've uploaded an example, the red column C is what I need