+---+---+---+---+---+---+
6 | A |   |               |
  +   +   +---+---+---+   +
5 |   | B             |   |
  +   +---+---+---+   +   +
4 |           |   |   | F |
  +---+   +---+   +---+---+
3 |   |   | C             |
  +   +---+---+---+   +---+
2 |             D |   |   |
  +   +---+---+---+---+   +
1 |   |             E     |
  +---+---+---+---+---+---+
    a   b   c   d   e   f

f5 = A
e4 = A
d3 = A
d4=/=B
d4 = E
a5=/=C
b6=/=D
b3=/=D
a5=/=D
a4 = D
b4 = C
c4 = B
b1 = D
c1 = A
b2 = A
b6=/=E
c5 = E
c2 = F
c6 = D
b6 = F
b3 = E
a5 = F
f6 = E
f3 = D
d5 = C
e5 = D


  +---+---+---+---+---+---+
  | A | F | D           E |
  +   +   +---+---+---+   +
  | F | B   E   C   D | A |
  +   +---+---+---+   +   +
  | D   C   B | E | A | F |
  +---+   +---+   +---+---+
  |   | E | C   A       D |
  +   +---+---+---+   +---+
  |     A   F   D |   |   |
  +   +---+---+---+---+   +
  |   | D   A       E     |
  +---+---+---+---+---+---+