You’re hosting a wedding at your home next summer, and the happy couple asked you to decorate the four gardens on the grounds with — let me check my notes — ah, fresh gridflowers. Gridflowers are planted in square plots. Each autumn, they cast seeds to all neighboring squares, including diagonals. The next spring, the old flowers are gone. A fresh flower will grow only in the spots that had exactly two neighboring flowers the year before (see examples below).
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