Problem:
Score : 100 points

Problem Statement

You are given three strings A, B and C. Check whether they form a word chain.

More formally, determine whether both of the following are true:

The last character in A and the initial character in B are the same.

The last character in B and the initial character in C are the same.

If both are true, print YES. Otherwise, print NO.

Constraints

A, B and C are all composed of lowercase English letters (a - z).

1 ≤ |A|, |B|, |C| ≤ 10, where |A|, |B| and |C| are the lengths of A, B and C, respectively.

Input

Input is given from Standard Input in the following format:

A B C

Output

Print YES or NO.

Sample Input 1

rng gorilla apple

Sample Output 1

YES

They form a word chain.

Sample Input 2

yakiniku unagi sushi

Sample Output 2

NO

A and B form a word chain, but B and C do not.

Sample Input 3

a a a

Sample Output 3

YES

Sample Input 4

aaaaaaaaab aaaaaaaaaa aaaaaaaaab

Sample Output 4

NO

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

import Control.Monad
import qualified Data.ByteString.Char8 as BS
import Data.Maybe (fromJust)
import Data.List as List
import Data.Array.ST
import Data.Array


isSiritori :: String -> String -> Bool
isSiritori a b = t == h
    where
        t = last a
        h = head b

solve :: String -> String -> String -> Bool
solve a b c = (isSiritori a b) && (isSiritori b c)

toYesNo :: Bool -> String
toYesNo True = "YES"
toYesNo _ = "NO"

main :: IO()
main = do
    (a:b:c:_) <- map BS.unpack . BS.words <$> BS.getLine
    putStrLn $ toYesNo $ solve a b c