+---------+ +--------+
| Bonn | --> | Berlin |
+---------+ +--------+
|
|
v
+---------+ +--------+
| Cottbus | --> | Ulm |
+---------+ +--------+
+---------+ +--------+
| Bonn | --> | Berlin |
+---------+ +--------+
|
|
v
+---------+ +--------+
| Cottbus | --> | Ulm |
+---------+ +--------+