7
0 23 25 20 15 18 18 
23 0 10 9 12 9 9 
25 10 0 7 12 7 7 
20 9 7 0 9 4 4 
15 12 12 9 0 9 5 
18 9 7 4 9 0 4 
18 9 7 4 5 4 0