20
12 13 15 14 16 18 19 17 20 11 
16 14 18 15 13 12 19 17 20 11 
15 16 12 20 14 17 13 11 19 18 
12 11 14 18 16 15 20 13 17 19 
17 13 14 12 18 11 16 20 15 19 
20 11 18 13 15 16 17 19 14 12 
16 15 20 13 12 19 18 14 11 17 
12 15 11 13 20 14 17 16 18 19 
17 13 18 16 14 12 20 19 11 15 
20 12 11 17 15 16 19 13 18 14 
10 9 1 7 3 4 8 5 2 6 
6 3 2 9 1 7 5 10 4 8 
9 5 3 7 10 4 6 1 2 8 
8 2 7 9 3 10 5 6 1 4 
9 5 4 2 10 1 7 6 3 8 
1 4 8 6 10 3 9 2 7 5 
6 1 7 3 5 8 4 10 2 9 
8 7 9 1 2 6 3 5 10 4 
6 4 7 8 10 5 3 1 2 9 
3 8 6 2 10 7 1 5 4 9 
forbidden 1 12
forbidden 1 13
forbidden 1 15
forbidden 1 17
forbidden 1 19
forbidden 2 14
forbidden 2 16
forbidden 3 13
forbidden 3 14
forbidden 4 16
forbidden 4 17
forbidden 4 19
forbidden 5 17
forbidden 6 19
forbidden 6 20
forbidden 7 11
forbidden 7 12
forbidden 7 14
forbidden 7 15
forbidden 7 16
forbidden 7 17
forbidden 7 20
forbidden 8 13
forbidden 9 11
forbidden 9 12
forbidden 9 13
forbidden 9 14
forbidden 9 16
forbidden 9 20
forbidden 10 11
forbidden 10 12
forbidden 10 14
forbidden 10 15
forbidden 10 19