Last of the Kellers, and the hardest. You really can’t say I wasn’t prepared.

**Rules** The left grid is a Japanese Sums puzzle, digits 1-8. Place digits in some cells, so that they don’t repeat in rows or columns. Clues give the sums of blocks of adjacent digits in order. The right grid is a Dotted Snake: Draw a snake of any length that occupies full cells and doesn’t touch itself, not even diagonally. Numbering the snake cells from head to tail, put a dot in every third cell, starting with the third. Clues indicated the number of dotted snake cells in the corresponding row or column.

The grids interact: There must be a digit under every snake cell, and that digit must be divisible by three if and only if the corresponding snake cell is dotted.