.
                                    red
                       ­      yellow blue
                         red yellow blue
                        red yellow blue re
                          yellow blue red
                          yellow blue red
                          yellow blue red
                          yellow blue red
                          yellow blue red
                          yellow blue red    
                          yellow blue red
                          yellow blue red
                          yellow blue red
                          yellow blue red
                          yellow blue red
                 yellow                  blue red
         yellow blue red    yellow blue red
      yellow blue red yel low blue red yello
        blue red yellow        blue red yellow
             blue red                      yellow