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