deconv3(g, f):
-6 -8 -5 9
-7 9 -6 -8
2 -7 9 8

7 4 4 -6
9 9 4 -4
-3 7 -2 -3

deconv3(g, h):
-9 5 -8
3 5 1

-1 -7 2
-5 -6 6

8 5 8
-2 -6 -4