Problem:
Score : 200 points

Problem Statement

You are given a string S consisting of lowercase English letters. Determine whether all the characters in S are different.

Constraints

2 ≤ |S| ≤ 26, where |S| denotes the length of S.

S consists of lowercase English letters.

Input

Input is given from Standard Input in the following format:

S

Output

If all the characters in S are different, print yes (case-sensitive); otherwise, print no.

Sample Input 1

uncopyrightable

Sample Output 1

yes

Sample Input 2

different

Sample Output 2

no

Sample Input 3

no

Sample Output 3

yes

Solution in Haskell (GHC 7.10.3) (judge verdict: Accepted)

{-# LANGUAGE BangPatterns #-}
module Main (main) where

import Data.ByteString (ByteString)
import qualified Data.ByteString.Char8 as C8
import Data.Bool
import Data.List

main :: IO ()
main = do
  readStrings >>= print . showAnswer . solve . head

type Input  = String
type Output = Bool

solve :: String -> Output
solve = all ((==1) . length) . group . sort

showAnswer :: Output -> Answer
showAnswer = String . bool "no" "yes"

-- utils
readStrings :: IO [String]
readStrings = map C8.unpack . C8.words <$> C8.getLine

data Answer
  = YesNo Bool
  | YESNO Bool
  | AB Bool
  | Number Int
  | String String
  | ByteString ByteString
  | Compare Ordering
  | Compare2 Ordering

instance Show Answer where
  show (YesNo b)       = bool "No" "Yes"  b
  show (YESNO b)       = bool "NO" "YES"  b
  show (AB b)          = bool "B"  "A"    b
  show (Number i)      = show i
  show (String s)      = s
  show (ByteString bs) = C8.unpack bs
  show (Compare o)     = ordering "<" "=" ">" o
  show (Compare2 o)    = ordering "Right" "Balanced" "Left" o

ordering :: a -> a -> a -> Ordering -> a
ordering lt eq gt o = case o of
  LT -> lt
  EQ -> eq
  GT -> gt

-- | k 番目の文字に関数 f を適用する
indexMapBS :: Int -> (Char -> Char) -> ByteString -> ByteString
indexMapBS k f s = C8.concat [s1, C8.singleton (f c), s3]
  where
    (s1, s2) = C8.splitAt (k-1) s
    c = C8.head s2
    s3 = C8.tail s2