Normal sudoku rules apply. The four hungry hungry hippos on the edges of the grid are fighting to eat all of the large circles in the grid. If a circle is entirely within the colored territory of a single hippo, that circle will be eaten by that hippo. If a circle is on the border between multiple hippos' territories, which hippo eats that circle must be determined. A number on a hippo shows the sum of all circles that it eats. A digit on a circle indicates how many circles contain that digit. Digits separated by a small white dot are consecutive. These dots are too small for the hippos to care about, so they are not eaten. Not all possible dots are shown.