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