--
-- The Computer Language Shootout
-- http://shootout.alioth.debian.org/
--
-- Contributed by Don Stewart
-- Based on older versions by Greg Buchholz, 
-- Mirko Rahn, Chris Kuklewicz and David Himmelstrup
--
import Data.Char
#ifndef __NHC__
import Data.ByteString.Base
import qualified Data.ByteString.Char8 as B
#else
import Prelude as B
#endif

main = print . new 0 =<< B.getContents

new i s
    | B.null s  = i
    | x == '-'  = sub i 0 xs
    | otherwise = add i (parse x) xs

    where (x,xs) = uncons s

sub i n t | i `seq` n `seq` t `seq` False = undefined
sub i n t | y == '\n'  = new (i-n) ys
          | otherwise  = sub i n' ys
  where (y,ys) = uncons t
        n'      = parse y + 10 * n

add i n t | i `seq` n `seq` t `seq` False = undefined
add i n t | y == '\n' = new (i+n) ys
          | otherwise = add i n' ys
  where (y,ys) = uncons t
        n'      = parse y + 10 * n

parse c  = ord c - ord '0'

#ifndef __NHC__
uncons s = (w2c (unsafeHead s), unsafeTail s)
#else
uncons (x:xs) = (x,xs)
#endif