Which point is a reflection of point A over the line y=x?
A(2, 6), B(6, 6) and C(6, 3) are the coordinates of a triangle. D, E and F are the reflection points of A, B and C respectively about X = 0. G, H and K are the reflection points of D,E and F respectively about Y = 1. The value of (sum of the y - coordinates of H and K) - (sum of the x - coordinates of G and H) is