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