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