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)

s = gets.strip
n = s.size

def parindrome?(str)
  ar = str.chars
  
  while ar.size > 1 do
    head = ar.shift
    last = ar.pop
    return false if head != last
  end

  true
end

fhalf = s[0...((n-1)/2)]
lhalf = s[((n+3)/2-1..-1)]

if parindrome?(s) && parindrome?(fhalf) && parindrome?(lhalf)
  puts 'Yes'
else
  puts 'No'
end