[(0,1),(0,2),(2,3),(1,4),(3,4),(2,5),(5,6),(1,6),(6,7),(4,7),(7,8),(8,9),(5,9),(3,10),(9,10),(10,11),(8,12),(12,13),(11,13),(13,14),(14,15),(15,16),(11,16),(15,17),(16,17),(12,18),(14,18),(17,19),(19,20),(19,21),(20,22),(21,22),(21,23),(22,24),(18,25),(23,26),(20,27),(23,28)]
[(0,1),(1,2),(0,2),(2,3),(1,3),(3,4),(4,5),(4,6),(5,7),(6,8),(7,8),(7,9),(9,10),(6,11),(11,12),(10,13),(8,13),(10,14),(12,14),(5,15),(9,16),(13,17),(15,18),(11,18),(14,19),(16,19),(17,20),(19,21),(12,21),(20,22),(15,22),(16,23),(20,23),(18,24),(17,25),(21,26),(22,27),(23,28)]
