13
 0     0   5   0   9  -9  18  -18
 1     6   4   3  -6  12 -15     
 2    12   4  -3   6 -12  15     
 3    18   5   0   9  -9  18  -18
 4    24   4   3  -6  12 -15     
 5    30   4  -3   6 -12  15     
 6    36   5   0   9  -9  18  -18
 7    42   4   3  -6  12 -15     
 8    48   4  -3   6 -12  15     
 9    54   5   0   9  -9  18  -18
10    60   4   3  -6  12 -15     
11    66   4  -3   6 -12  15     
12    72   5   0   9  -9  18  -18
