Problem:
Score : 500 points

Problem Statement

You have a string A = A_1 A_2 ... A_n consisting of lowercase English letters.

You can choose any two indices i and j such that 1 \leq i \leq j \leq n and reverse substring A_i A_{i+1} ... A_j.

You can perform this operation at most once.

How many different strings can you obtain?

Constraints

1 \leq |A| \leq 200,000

A consists of lowercase English letters.

Input

Input is given from Standard Input in the following format:

A

Output

Print the number of different strings you can obtain by reversing any substring in A at most once.

Sample Input 1

aatt

Sample Output 1

5

You can obtain aatt (don't do anything), atat (reverse A[2..3]), atta (reverse A[2..4]), ttaa (reverse A[1..4]) and taat (reverse A[1..3]).

Sample Input 2

xxxxxxxxxx

Sample Output 2

1

Whatever substring you reverse, you'll always get xxxxxxxxxx.

Sample Input 3

abracadabra

Sample Output 3

44

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

import qualified Data.ByteString.Lazy.Char8 as B
import Data.Maybe
import qualified Data.Vector.Unboxed as V
import qualified Data.Vector.Unboxed.Mutable as VM
import Data.Char
import Data.List
import Control.Monad

bsReadInts :: B.ByteString -> [Int]
bsReadInts = map (fst . fromJust . B.readInt) . B.words

solve :: String -> Int
solve a = 1 + answer
  where
    vec = V.create $ do
      v <- VM.replicate 26 0
      forM a $ \c -> do
        let idx = ord c - ord 'a'
        when (idx >= 0 && idx < 26) (VM.modify v (+ 1) idx)
      return v
    lst = V.toList vec
    answer = sum $ zipWith (*) lst $ map sum $ tail (tails lst)

main :: IO ()
main = do
  cont <- getContents
--  cont <- B.getContents
--  let answer = solve (B.unpack cont)
  let answer = solve cont
  putStrLn $ show answer