7
0 25 21 18 13 18 17 
25 0 10 9 12 7 8 
21 10 0 7 14 7 8 
18 9 7 0 11 4 5 
13 12 14 11 0 9 6 
18 7 7 4 9 0 3 
17 8 8 5 6 3 0