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