The objective of sudoku is to fill a grid of 9 × 9 cells (81 squares) divided into 3 × 3 subgrids (also called "boxes" or "regions") with the figures 1 to 9 starting from some numbers already arranged in some of the cells. The initial form of the game is that there are nine different elements, which must not be repeated in the same row, column or subgrid. A well-planned sudoku can only have one solution, and must have at least 17 initial clues. The solution to a sudoku is always a Latin square, although the converse is not generally true since sudoku establishes the added restriction that The same number cannot be repeated in a subgrid.