Normal sudoku rules apply. There are clues outside the grid. Each side either contains all Sandwich clues, or all X-Sum clues. Which side contains which type of clue is to be determined by the solver. A sandwich clue gives the total of the digits placed between 1 and 9 in the row or column. An X-Sum clue gives the sum of the first X cells that are seen in the row or column from the clue, where X is the first seen cell (i.e. a clue of 8 could be satisfied by 26 or 314 or 341).