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MathNet 2018-part-02 — 181 problems (EN–VI) Question 21

Math Olympiad Vault · MathNet 2018-part-02 — 181 problems (EN–VI)

Question 21

We say that a circular arrangement of positive integers is alternating if every number is either smaller, or larger than both of its neighbours. We call a pair of adjacent numbers good if, upon its removal, the remaining numbers form an alternating arrangement.

The numbers $1$ to $300$ are placed on a circle in an alternating arrangement. Determine the least possible number of good pairs of adjacent numbers in such arrangement.