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