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) {
		new Calc().Solve();
	}
	public class Calc {
		private Utils.Scan cin = new Utils.Scan();
		public Calc() { }
		public void Solve() {
			var item=Console.ReadLine().Split(' ').ToArray();
			if (item[1][0] == item[0].Last() && item[1].Last() == item[2][0]) {
				Console.WriteLine("YES");
			} else {
				Console.WriteLine("NO");
			}
			return;
		}
	}
}
public static class Utils {
	public class Scan {
		public Scan() { }
		public int ReadInt() => Console.ReadLine().IntParse();
		public int[] ReadInt(char separator) => Console.ReadLine().Split(separator).Select(int.Parse).ToArray();
		public double ReadDouble() => double.Parse(Console.ReadLine());
		public double[] ReadDouble(char separator) => Console.ReadLine().Split(separator).Select(double.Parse).ToArray();
		public long ReadLong() => long.Parse(Console.ReadLine());
		public long[] ReadLong(char separator) => Console.ReadLine().Split(separator).Select(long.Parse).ToArray();
	}
	public static string Docking<T>(this IEnumerable<T> list, Func<T, string> filter = null) {
		StringBuilder sb = new StringBuilder();
		foreach (var item in list) {
			sb.Append(filter == null ? item.ToString() : filter(item));
		}
		return sb.ToString();
	}
	public static int IntParse(this string s) => int.Parse(s);
}