[(0,1),(1,2),(1,3),(2,4),(2,5),(0,5),(4,6),(3,6),(3,7),(5,8),(8,9),(4,10),(6,10),(10,11),(11,12),(9,12),(7,13),(11,13),(13,14),(8,15),(7,16),(9,17),(12,18)]
[(0,1),(1,2),(0,2),(1,3),(2,4),(3,5),(4,6),(5,7),(4,8),(7,8),(3,9),(6,9),(8,10),(5,11),(7,11),(6,12),(12,13),(10,13),(13,14),(12,15),(10,16),(9,17),(11,18)]
