discovery and finishing times
  shirt        1/8
  tie          2/5
  jacket       3/4
  belt         6/7
  watch        9/10
  undershorts  11/16
  pants        12/15
  shoes        13/14
  socks        17/18

the graph is a DAG

topological order (decreasing finishing time)
  socks undershorts pants shoes watch shirt belt tie jacket 

verification: every arc goes left to right
  shirt        -> tie      position 5 -> 7   ok
  shirt        -> belt     position 5 -> 6   ok
  tie          -> jacket   position 7 -> 8   ok
  belt         -> jacket   position 6 -> 8   ok
  undershorts  -> pants    position 1 -> 2   ok
  undershorts  -> shoes    position 1 -> 3   ok
  pants        -> shoes    position 2 -> 3   ok
  pants        -> belt     position 2 -> 6   ok
  socks        -> shoes    position 0 -> 3   ok

all arcs respected.
