.0      .1      .2      .3      .4      .5      .6      .7      .8      .9
     0       0       0       0       0       0       0       0       0       0       0
     1       0       0       0       0       0       0       0       0       0       0
     2       0       0       0       0       0       0       0       0       0       0
     3       0       0       0       0       0       0       0       0       0       0
     4       0       0       0       0       0       0       0       0       0       0
     5       0       0       0       0       0       0       0       1       1       1
     6       1       1       1       1       1       1       1       1       1       1
     7       1       1       1       1       1       1       1       2       2       2
     8       2       2       2       2       2       2       2       2       3       3
     9       3       3       3       3       3       3       4       4       4       4
    10       4       4       4       5       5       5       5       5       6       6
    11       6       6       6       7       7       7       7       7       8       8
    12       8       8       9       9       9      10      10      10      11      11
    13      11      12      12      12      13      13      13      14      14      15
    14      15      15      16      16      17      17      18      18      19      20
    15      20      21      21      22      23      24      24      25      26      27
    16      27      28      29      30      31      32      33      34      35      37
    17      38      39      40      42      43      45      46      48      49      51
    18      52      54      56      58      60      62      64      66      68