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MathNet 2018-part-04 — 181 problems (EN–VI) Question 80

Math Olympiad Vault · MathNet 2018-part-04 — 181 problems (EN–VI)

Question 80

Alina and Bogdan play the following game. They have a heap of $330$ pebbles. The two players move alternately. In one move one takes $1$, $n$ or $m$ pebbles from the heap. The player who takes the last pebble wins the game. Before starting, Alina chooses the number $n$, $(1 \lt n \lt 10)$, after which Bogdan chooses the number $m$, $(m \neq n$, $1 \lt m \lt 10$). Alina moves first. Which of the two players has a winning strategy? What if at the beginning there are $2018$ pebbles in the heap?