7
0 21 20 15 13 16 16 
21 0 11 8 10 7 7 
20 11 0 7 13 8 8 
15 8 7 0 8 3 3 
13 10 13 8 0 7 5 
16 7 8 3 7 0 2 
16 7 8 3 5 2 0