MathDB
USAMO 2000 Problem 4

Source:

October 1, 2005
USA(J)MOUSAMOinductionpigeonhole principleContradictioncombinatoricsgrid

Problem Statement

Find the smallest positive integer nn such that if nn squares of a 1000×10001000 \times 1000 chessboard are colored, then there will exist three colored squares whose centers form a right triangle with sides parallel to the edges of the board.
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