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