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