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 Ruby (2.3.3) (judge verdict: Runtime Error)

  n, t_max = gets.chomp.split(" ").map(&:to_i)
  t = gets.chomp.split(" ").map(&:to_i)
  sum = 0
  (n-1).times do |i|
    if t_max > (t[i+1]-t[i])
      sum += (t[i+1]-t[i])
    elsif t_max <= (t[i+1]-t[i])
      sum += t_max
    end
  end
  sum += t_max
  puts sum