Place the digits 0-9 once into each row, column, and region. Identical digits may not be separated by a knight's move. The digits 0 and 9 may not be orthogonally or diagonally adjacent to each other or themselves. A clue outside the grid is either an X-Sums clue or a Sandwich clue, but not both, i.e. exactly one of the following is true: the clue gives the sum of the digits between the 0 and 9 in the indicated row or column; or the clue gives the sum of the first X digits in that row or column, starting from the digit next to the clue, which is equal to X. The ? may be any valid clue.