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2023 China TST Problem 9

Source: 2023 China TST Problem 9

March 18, 2023
combinatoricsChina TST

Problem Statement

Find the largest positive integer mm which makes it possible to color several cells of a 70×7070\times 70 table red such that [*] There are no two red cells satisfying: the two rows in which they are have the same number of red cells, while the two columns in which they are also have the same number of red cells; [*] There are two rows with exactly mm red cells each.