module Exercise_7 where
import Data.List
import Control.Monad
import Data.Ord
import qualified Data.Set as Set

{-WETT-}
wettComp xs (dA,(xA,yA)) = [(dA + dB, (xA, yB)) | (dB, (xB,yB)) <- xs, yA == xB]
minOfOne y = minimumBy (comparing fst) . filter ((y ==) . snd)
trancl xs = iterate (nub . (map =<< (. snd) . flip minOfOne)  . ap union ((=<<) =<< wettComp)) xs !! (2*length xs)
{-TTEW-}