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