7
0 28 25 21 13 18 18 
28 0 13 9 15 10 10 
25 13 0 8 18 11 11 
21 9 8 0 12 5 5 
13 15 18 12 0 11 7 
18 10 11 5 11 0 4 
18 10 11 5 7 4 0