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;
using System.Threading.Tasks;

namespace ConsoleApp33 {
    class Program {
        static void Main(string[] args) {
            var X = Console.ReadLine().Split(' ').ToArray();
            string A = X[0];
            string B = X[1];
            string C = X[2];

            //各文字列の長さ
            int len_A = X[0].Length;
            int len_B = X[1].Length;
            int len_C = X[2].Length;

            if (A[len_A - 1] == B[0] && B[len_B - 1] == C[0]) {
                Console.WriteLine("YES");
            } else {
                Console.WriteLine("NO");
            }
        }
    }
}