7
0 20 22 18 13 17 16 
20 0 10 8 11 7 8 
22 10 0 8 13 7 8 
18 8 8 0 9 3 4 
13 11 13 9 0 8 5 
17 7 7 3 8 0 3 
16 8 8 4 5 3 0