8
0   23  12  999 999 999 999 999
23  0   25  999 22  999 999 35
12  25  0   18  999 999 999 999
999 999 18  0   999 20  999 999
999 22  999 999 0   23  14  999
999 999 999 20  23  0   24  999
999 999 999 999 14  24  0   16
999 35  999 999 999 999 16  0
4