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