12
                                                     +---------+
                                                     |:::::::::|
                                                     |:::::::::|
                                                     |:::::::::|
                                                     |:::::::::|
                                                     |:::::::::|
                                                     +---------+

                 +-----------------------------+
                 |*****************************|
                 |*****************************|
                 |*****************************|
                 |*****************************|
                 |*****************************|
9                |*****************************|                      3
                 |*****************************|
                 |*****************************|
                 |*****************************|
                 |*****************************|
                 |*****************************|
                 +-----------------------------+





                                   +---------+
                                 6 |:::::::::|
                                   |:::::::::|
                                   |:::::::::|
                                   |:::::::::|
                                   |:::::::::|
                                   +---------+