
--{-# LANGUAGE StandaloneDeriving #-}
--{-# LANGUAGE BangPatterns #-}

module Main where

import Debug.Trace
--import Data.List
--import Data.Char
--import qualified Data.Set.Strict as Set
--import qualified Data.Map.Strict as Map

main :: IO ()
main = do
  a <- read <$> getLine
  --a `traceShow`
  print $ solve a

solve :: Int -> Int
solve a
  | a > 1000 = solve (a - 1000)
  | otherwise = 1000 - a
