Fill some cells in the grid with the digits 1–9 such that no digit repeats in a row or column. Cells containing a circle, square, or arrow must have a digit in them. Digits along an arrow must sum to the digit in the circle. Gray squares contain even digits and gray circles contain odd digits. A region is a collection of orthogonally connected cells. A region of size n contains the digits 1 through n once each. Regions may not touch each other orthogonally, although they may touch each other diagonally.