Normal sudoku rules apply. You must shade some cells to satisfy all of the following rules: All shaded squares are orthogonally connected; no 2x2 region is entirely shaded or entirely unshaded; no group of unshaded cells is enclosed by shaded cells; clues outside the grid give the sum of the shaded cells in that row/column; all circled cells are shaded; and the digit in a circle matches the number of shaded cells within that box (counting itself).