the shortest path has length 21
the cities on the shortest path are:
  1 8 3 5 6 2 4 7 
RTS warning: blocked process: Worker.worker : file shared.mpd, line 50
RTS warning: blocked process: Worker.worker : file shared.mpd, line 50
RTS warning: blocked process: Worker.worker : file shared.mpd, line 50
RTS warning: blocked process: Worker.worker : file shared.mpd, line 50