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