IMO Shortlist 1988 problem 14


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2. travnja 2012.
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For what values of n does there exist an n \times n array of entries -1, 0 or 1 such that the 2 \cdot n sums obtained by summing the elements of the rows and the columns are all different?
Izvor: Međunarodna matematička olimpijada, shortlist 1988