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++14 (GCC 5.4.1) (judge verdict: Accepted)

#include <iostream>
#include <cstdio>
#include <algorithm>
#include <cstdlib>
#include <cstring>
#include <cmath>
#include <vector>
#pragma warning(disable : 4996)

using namespace std;

#define FOR(i,a,b) for (int i = (a); i < (b); i++)
#define REP(i,n) FOR(i,0,n)

//最大公約数
long gcd(long a, long b){
	if (a%b==0){
		return b;
	}
	else{
		return gcd(b,a%b);
	}
}

//最小公倍数
long lcm(long a, long b){
	return (a*b) / gcd(a,b);
}

template<typename A, typename B> inline bool chmax(A &a, B b) { if (a < b) { a = b; return 1; } return 0; }
template<typename A, typename B> inline bool chmin(A &a, B b) { if (a > b) { a = b; return 1; } return 0; }

typedef long long ll;

const ll INF = 1ll<<29;
const ll MOD = 1000000007;
const double EPS = 1e-10;

char str[12];

int main(){
	char tmp;
	int f = 0;
	
	REP(i,3){
		scanf("%s", str);
		
		int len = strlen(str);
		
		if (i){
			if (tmp != str[0]){
				f = 1;
				break;
			}
		}
		
		tmp = str[len-1];
	}
	
	if (f) cout << "NO" << endl;
	else cout << "YES" << endl;
	
	return 0;
}