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;

class Program
{
    static string InputPattern = "InputX";

    static List<string> GetInputList()
    {
        var WillReturn = new List<string>();

        if (InputPattern == "Input1") {
            WillReturn.Add("rng gorilla apple");
            //YES
        }
        else if (InputPattern == "Input2") {
            WillReturn.Add("yakiniku unagi sushi");
            //NO
        }
        else if (InputPattern == "Input3") {
            WillReturn.Add("a a a");
            //YES
        }
        else if (InputPattern == "Input4") {
            WillReturn.Add("aaaaaaaaab aaaaaaaaaa aaaaaaaaab");
            //NO
        }
        else {
            string wkStr;
            while ((wkStr = Console.ReadLine()) != null) WillReturn.Add(wkStr);
        }
        return WillReturn;
    }

    static void Main()
    {
        List<string> InputList = GetInputList();
        string[] wkArr = InputList[0].Split(' ');

        string A = wkArr[0];
        string B = wkArr[1];
        string C = wkArr[2];

        bool IsOK = true;
        if (A.Last() != B[0]) IsOK = false;
        if (B.Last() != C[0]) IsOK = false;
        Console.WriteLine(IsOK ? "YES" : "NO");
    }
}