ReadNTuples.hs

module Throwaway where

import           Control.Monad
import           ConvexHull                     ( grahamScan
                                                , perimeter
                                                )
import           Text.Printf

h :: [Int] -> (Int, Int)
h (x : y : []) = (x, y)

readTuple :: IO (Int, Int)
readTuple = do
  s <- getLine
  return $ h (map read $ words s)

getPoints :: Int -> IO [(Int, Int)]
getPoints n = replicateM n readTuple

main :: IO ()
main = do
  n      <- readLn :: IO Int
  points <- getPoints n
  printf "%.1f\n" $ perimeter . grahamScan $ points