class Sudoku_chart():
    def __init__(self, dim=9, block_dim=3):
            self.dim=dim            #размер матрицы (9*9)
            self.block_dim=block_dim        #размер блока    (3*3)
            self.matrix=map(list,[[None]*dim]*dim)

    def _get_row(self, row):
            return self.matrix[row]

    def _get_col(self, col):
            return [row[col] for row in self.matrix]

    def _get_block(self, block_x, block_y): #x, y - координаты блока     (00,    01, 02)
            x=self.block_dim*block_x        #               (10,    11, 12)
            y=self.block_dim*block_y        #               (20,    21, 22)

            values=set()
            for row in self.matrix[y:y+self.block_dim]:
                values.update(row[x:x+self.block_dim])
            return values

        def get_cross(self, row, col):
            values=set()
            values.update(self._get_row(row),
                          self._get_col(col),
                          self._get_block(col/self.block_dim,
                                          row/self.block_dim))
            return values

    def set_cell(self, row, col, value):
            self.matrix[row][col]=value

        def __repr__(self):
            output=str()
            for row in self.matrix:
                for block in xrange(0, self.dim, self.block_dim):
                    for val in row[block:block+self.block_dim]:
                        output+=str(val)+', '
                    output+='\t'
                output+='\n'
            return output