import Data Char import System IO isUnreserved elem -_ urlencode urlen

import Data.Char
import System.IO

isUnreserved c =
       c >= 'A' && c <= 'Z' || c >= 'a' && c <= 'z' || c >= '0' && c <= '9'
    || c `elem` "-_.~"

urlencode [] = []
urlencode (' ':tail) = '+' : urlencode tail
urlencode (c:tail)
    | isUnreserved c = c : urlencode tail
    | otherwise = '%' : intToDigit d1 : intToDigit d2 : urlencode tail where (d1, d2) = ord c `divMod` 16

main = hSetBinaryMode stdin True >> interact urlencode