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Inverse LITSO (396)
Instruction:
Shade exactly four connected cells in each outlined region to form a tetromino, so that the following conditions are true: (1) All unshaded cells are connected into one large shape along their edges; (2) No 2×2 group of cells can be entirely unshaded; (3) When two tetrominoes share an edge, they must not be of the same shape, regardless of rotations or reflections.