Middle European Mathematical Olympiad 2022 Problem I-2
Let be a positive integer. Anna and Beatrice play a game with a deck of cards labelled with the numbers . Initially, the deck is shuffled. The players take turns, starting with Anna. At each turn, if denotes the number written on the topmost card, then the player first looks at all the cards and then rearranges the topmost cards. If, after rearranging, the topmost card shows the number again, then the player has lost and the game ends. Otherwise, the turn of the other player begins. Determine, depending on the initial shuffle, if either player has a winning strategy, and if so, who does.