# node lists on both sides
[ Ulm ], [ Hahn ], [ Wismar ] => [ Frankfurt ]
[ Frankfurt ] => [ Stuttgart ], [ Trier ]
[ Potsdam ], [ Cuixhaven ] => [ Bremerhaven ], [ Wismut ]
# node lists on both sides
[ Ulm ], [ Hahn ], [ Wismar ] => [ Frankfurt ]
[ Frankfurt ] => [ Stuttgart ], [ Trier ]
[ Potsdam ], [ Cuixhaven ] => [ Bremerhaven ], [ Wismut ]