Example Input:
 Edges: (from_node, to_node)
  0,8
  1,9
  1,10
  2,8
  2,11
  3,9
  3,11
  4,8
  4,10
  4,11
  5,9
  5,10
  5,11
  6,10
  6,12
  7,11
  7,13
  7,14

* required field