[(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),(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)]
