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: Runtime Error)

        using System;
        using System.Linq;
        using System.Collections.Generic;
        using static System.Math;
 
        public class Program
        {
            public static void Main(string[] args)
            {
            int[] input = Console.ReadLine().Split(' ').Select(int.Parse).ToArray();
            int[] sec = Console.ReadLine().Split(' ').Select(int.Parse).ToArray();
            int sum = sec[0] == 0? input[1]: 0;
            int stock = 0;
 
            for(int i = 1; i < input[0]; i++)
            {
                if(sec[i] - sec[i - 1] >= input[1])
                {
                    sum += input[1];
                }
                else
                {
                    stock = sec[i];
                }
            }
 
            Console.WriteLine(sum + stock);
            }
        }