i = 1 4,-1&1,1: 3 i = 2 1,1&4,1: 3 i = 3 4,1&7,0: 2 i = 4 6,0&7,-1: 6 i = 5 6,-1&1,0: 2 ......... ....*.... .../#\... ../###\.. .*#####*. .|#####|. .*=====*. .........