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MathNet 2006 — Part 02 Question 120

Math Olympiad Vault · MathNet 2006 — Part 02

Question 120

Tokens are placed in some of the cells of a table of size $8 \times 8$ such that:

(1) there is at least one token in any rectangle of size $2 \times 1$ and $1 \times 2$;

(2) there are two neighboring tokens in any rectangle of size $7 \times 1$ and $1 \times 7$.

Find the minimum possible number of tokens.