A Sudoku puzzle consists of 9 x 9 cells subdivided into 9 regions with 3 x 3 cells. The rules are simple. There have to be the numbers from 1 to 9 in every row, column and region. In the beginning some numbers are given. These cells are painted with cyan background color. The aim of the puzzle is to find the missing numbers. There is only one solution of a Sudoku puzzle.