fctrl.hs

-- file: fctrl.hs
-- http://www.codechef.com/problems/FCTRL/
{-# LANGUAGE BangPatterns #-}
{-# OPTIONS_GHC -O2 #-}
module Main where

import qualified Data.ByteString.Char8 as S
import IO

main :: IO ()
main = mapM_ (print . fctrl) . tail . readInts =<< S.getContents
  where
    readInts s = case S.readInt s of -- lazily reads current line
                 Nothing     -> []
                 Just (k,t)  -> k : readInts (S.tail t)

fctrl :: Int -> Int
fctrl = fctrl' 0
    where 
        fctrl' :: Int -> Int -> Int
        fctrl' r n | n < 5 = r
                   | otherwise = fctrl' (r + n') n'
          where n' = div n 5