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