Problem:
Score : 200 points

Problem Statement

You are given a string s consisting of lowercase English letters. Extract all the characters in the odd-indexed positions and print the string obtained by concatenating them. Here, the leftmost character is assigned the index 1.

Constraints

Each character in s is a lowercase English letter.

1≤|s|≤10^5

Input

The input is given from Standard Input in the following format:

s

Output

Print the string obtained by concatenating all the characters in the odd-numbered positions.

Sample Input 1

atcoder

Sample Output 1

acdr

Extract the first character a, the third character c, the fifth character d and the seventh character r to obtain acdr.

Sample Input 2

aaaa

Sample Output 2

aa

Sample Input 3

z

Sample Output 3

z

Sample Input 4

fukuokayamaguchi

Sample Output 4

fkoaaauh

Solution in Haskell (GHC 7.10.3) (judge verdict: Wrong Answer)

import Control.Applicative
import Control.Monad
import Data.List
import Data.Char
strToInt s = (read :: String -> Int) s
strToInteger s = (read :: String -> Integer) s
strToDouble s = (read :: String -> Double) s

main :: IO ()
main = do
    -- 文字列の入力
    s <- getLine
    -- 出力
    putStrLn $ show $ solve s

solve :: String -> String
solve [] = []
solve s = (head s):(solve (drop 2 s))