In each puzzle, shade in some of the squares so that:
1) no shaded squares are adjacent (including diagonally),
2) there is exactly one shaded square in each row and in each column,
3) no square containing a number can be shaded, and
4) each number should be equal to the number of adjacent (including diagonally) shaded squares.
Each puzzle has a unique solution. All puzzles copyright Erich Friedman, 2010.