# 1, 2 or 3 stones?

Logic Level 1

You play a game with a friend with a pile of 20 stones numbered 1~20. You take turns taking 1 stone, 2 consecutive stones, or 3 consecutive stones out of the pile. For example, in your turn, you can take out (19) or (11, 12) or (7, 8, 9) if they are still there. The player who takes the last stone wins.

If you go first, is there a strategy that guarantees you a win?


Clarification: The stones have to be consecutive, but they can be pulled from the middle of the group if you like. For example, on your first move, if you take out three stones, they don't need to be (1, 2, 3). They could, for example, be (11, 12, 13). And likewise for successive turns.

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