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 Rust (1.15.1) (judge verdict: Accepted)

use std::io::prelude;
use std::{io};
use std::collections::{HashMap, HashSet, VecDeque};
use std::cmp::Ordering;

fn string_to_nums(s: String) -> Vec<isize> {
    let mut v = Vec::new();
    for part in s.split_whitespace() {
        v.push(part.parse::<isize>().unwrap())
    }
    v
}

fn read_a_line() -> String {
    let mut s = String::new();
    assert!(io::stdin().read_line(&mut s).is_ok());
    s.trim().to_string()
}

fn read_nums() -> Vec<isize> {
    string_to_nums(read_a_line())
}

fn main() {
    let s = read_a_line();
    let mut ss:Vec<_> = s.as_str().split_whitespace().collect();
    let mut c:char = ss[0].chars().last().unwrap();
    for s in ss.into_iter().skip(1) {
        if s.chars().next().unwrap() != c { println!("NO"); return }
        c = s.chars().last().unwrap();
    }
    println!("YES");
}