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