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 C# (Mono 4.6.2.0) (judge verdict: Accepted)

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

class Program
{
    static void Main(string[] args)
    {
        string[] str = Console.ReadLine().Split(' ');
        int lengtha = str[0].Length;
        int lengthb = str[1].Length;
        string end_a = str[0].Substring(lengtha - 1, 1);
        string start_b = str[1].Substring(0, 1);
        string end_b = str[1].Substring(lengthb - 1, 1);
        string start_c = str[2].Substring(0, 1);

        if(end_a == start_b && end_b == start_c){
            Console.WriteLine("YES");
        }else{
            Console.WriteLine("NO");
        }
    }
}