Divide the grid into polyominoes so that polyominoes of the same size (ie with the same number of cells) don't share an edge. Each cell contains a number equal to its polyomino's size. For each line, one circle contains an odd number, and the other an even. The odd circle gives the amount of odd numbers on the line (excluding itself), while the even circle gives the amount of even numbers (excluding itself). If an odd number is in a cell with an arrow, it gives the amount of odd numbers in that direction (excluding itself) and if the number is even, it gives the amount of even numbers (excluding itself).