// This is the solution obtained with Tabu Search by Cristina C. B. Cavalcante
// and Cid Carvalho de Souza. The optimality of this solution was proved by
// Susanne Heipcke.

82

1 2
2 9
3 15
4 21
5 27
6 33
7 21
8 28
9 35
10 42
11 49
12 35
13 43
14 51
15 60
16 69
17 1
18 8
19 59
20 68
21 77
