The demo file
 
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 instance demo
 
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 A simple demo. lower bound: 180
 4 5
 0 10 1 20 2 20 3 40 4 10
 1 20 0 10 3 30 2 50 4 30
 2 30 1 20 4 12 3 40 0 10
 4 50 3 30 2 15 0 20 1 15 
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