7
0 21 21 17 14 14 16 
21 0 12 10 11 11 9 
21 12 0 8 13 9 7 
17 10 8 0 9 5 3 
14 11 13 9 0 8 6 
14 11 9 5 8 0 2 
16 9 7 3 6 2 0