private Cell getChoice()
    {
        Cell choice = grid[0][0];
        for(int i=0; i<9; i++)
        {
            for(int j=0; j<9; j++)
            {
                int oldSize = choice.getPosNumbers().size();
                int newSize = grid[i][j].getPosNumbers().size();
                if( (oldSize==0 && newSize!=0) || (oldSize>2 && newSize<oldSize) )
                {
                    choice = grid[i][j];
                }
            }
        }
        return choice;
    }