0 1 2 3 4 5 6+ 0 1 2 3 4 5 6+ 0 1 2 3 4 5 6+ 0 1 2 3 4 5 6+ 0 1 2 3 4 5 6+ × 0 1 2 3 4 5+ × 0 1 2 3 4 5 × 0 1 2 3 4 5