2017 Polish Junior Math Olympiad First Round P3
Source: 2017 Polish Junior Math Olympiad First Round
May 23, 2023
combinatorics
Problem Statement
In each square of an board, we are to write one of the numbers , , or in such a way that the sum of the numbers in each column is nonnegative and the sum of the numbers in each row is nonpositive. What is the smallest number of zeros that can be written on the board? Justify your answer.