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Hojoo and Kestutis make moves in turn

Source: Germany Bundeswettbewerb Mathematik 2007, Round 2, Problem 2

July 18, 2008
combinatorics unsolvedcombinatorics

Problem Statement

At the start of the game there are r r red and g g green pieces/stones on the table. Hojoo and Kestutis make moves in turn. Hojoo starts. The person due to make a move, chooses a colour and removes k k pieces of this colour. The number k k has to be a divisor of the current number of stones of the other colour. The person removing the last piece wins. Who can force the victory?