IMO Shortlist 2012 problem C3


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3. studenoga 2013.
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In a 999 \times 999 square table some cells are white and the remaining ones are red. Let T be the number of triples (C_1,C_2,C_3) of cells, the first two in the same row and the last two in the same column, with C_1,C_3 white and C_2 red. Find the maximum value T can attain.
Izvor: Međunarodna matematička olimpijada, shortlist 2012