Shade exactly four connected cells in each outlined region to form a tetromino, so that the following conditions are true: (1) All tetrominoes are connected into one large shape along their edges; (2) No 2×2 group of cells can be entirely shaded; (3) When two tetrominoes share an edge, they must not be of the same shape, regardless of rotations or reflections. (Not all four letters have to be present in the grid; for example, it is possible for your solution to not have any "I" shapes.)
Regions with fewer than four cells will not have any shaded cells.
Notes:Variants:
- Additionally: Cells with an "X" (if given) are not part of any region.