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 OCaml (4.02.3) (judge verdict: Accepted)

open Batteries
let () =
  let a,b,c = Scanf.scanf "%s %s %s " (fun a b c -> a,b,c) in

  Printf.printf "%s\n" @@
  if 
    (String.sub a (String.length a - 1) 1) = (String.sub b 0 1) &&
    (String.sub b (String.length b - 1) 1) = (String.sub c 0 1)
  then "YES" else "NO"