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: Runtime Error)

solve :: [Integer] -> Integer -> Integer -> Integer -> Integer
solve [] _ _ acc = acc
solve (x:xs) end_of_water t acc
  | end_of_water <= x = solve xs (x+t) t (acc+t)
  | otherwise          = solve xs (x + t) t (acc - (end_of_water - x) + t)

main = do
     nt <- words <$> getLine
     let n = read $ (nt !! 0) :: Integer
     let t = read $ (nt !! 1) :: Integer
     -- putStrLn $ show $ n
     -- putStrLn $ show $ t

     ts_str <- words <$> getLine
     let ts = map (\s -> read s :: Integer) ts_str
     let ans = solve ts 0 t 0
     putStrLn $ show $ ans
     return ()