Help find maximum ac coefficient in DCT

[Osawa_Odessa]

I have an matrix 8x8 like this:
20 20 20 20 20 20 20 20
20 20 20 20 20 20 20 20
80 80 80 80 80 80 80 80
80 80 80 80 80 80 80 80
100 100 100 100 100 100 100 100
100 100 100 100 100 100 100 100
120 120 120 120 120 120 120 120
120 120 120 120 120 120 120 120
Now I apply DCT(Discrete Cosine Transform) to this matrix and I have F(u, v).
Could anyone help me find maximum AC coefficient?
I know the result is F(1,0) but can't explain why.