Place the digits 1-9 in every row, column and each marked 9-cell region. Cells separated by a single knight's move (in chess) cannot contain the same digit. Every 2x2 square of cells must contain at least one digit from (1,4,7), at least one digit from (2,5,8), and at least one digit from (3,6,9). Cells that are orthogonally adjacent cannot contain consecutive digits. Clues outside the grid give the sum of the digits along the indicated diagonal. The cell with a circle must contain an odd digit.