Normal sudoku rules apply. Cells separated by an X contain digits summing to 10. Not all Xs are given. Shade some cells in the grid such that all the following conditions are fulfilled: 1) All shaded cells are orthogonally connected, without creating a 2x2 area of shaded cells. 2) Groups of orthogonally connected unshaded cells form ‘islands’. Each island has exactly one circle, and the number in the circle shows the size of the island. Each island contains digits 1 to N without repeats, where N is the size of the island. Each island is of a different size.