Problem:
Score : 200 points

Problem Statement

A string S of an odd length is said to be a strong palindrome if and only if all of the following conditions are satisfied:

S is a palindrome.

Let N be the length of S. The string formed by the 1-st through ((N-1)/2)-th characters of S is a palindrome.

The string consisting of the (N+3)/2-st through N-th characters of S is a palindrome.

Determine whether S is a strong palindrome.

Constraints

S consists of lowercase English letters.

The length of S is an odd number between 3 and 99 (inclusive).

Input

Input is given from Standard Input in the following format:

S

Output

If S is a strong palindrome, print Yes;
otherwise, print No.

Sample Input 1

akasaka

Sample Output 1

Yes

S is akasaka.

The string formed by the 1-st through the 3-rd characters is aka.

The string formed by the 5-th through the 7-th characters is aka.
All of these are palindromes, so S is a strong palindrome.

Sample Input 2

level

Sample Output 2

No

Sample Input 3

atcoder

Sample Output 3

No

Solution in Ruby (2.3.3) (judge verdict: Accepted)

def palindrome?(t)
  ok = true
  for i in 0...(t.length / 2) do
    if t[i] != t[-1 - i]
      ok = false
      break
    end
  end
  return ok
end

s = gets.chomp
n = s.length
puts (palindrome?(s) && palindrome?(s.slice(0, (n - 1) / 2)) && palindrome?(s.slice((n + 1) / 2, (n - 1) / 2))) ? "Yes" : "No"