({{-1,3,-7},{0,2,-1},{1,-1,4}}-{{2,0,0},{0,2,0},{0,0,2}}).({{-1,3,-7},{0,2,-1},{1,-1,4}}-{{2,0,0},{0,2,0},{0,0,2}}).({{-1,3,-7},{0,2,-1},{1,-1,4}}-{{1,0,0},{0,1,0},{0,0,1}})

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