. 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 3 3 3 3 3 3 3 3 2 2 1 1 4 4 4 5 5 5 6 6 3.5 3.5 3.5 6.5 6.5 4 . . .