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)

# Wrote in Mar 22, 2020 22:36 by reetok
require 'time'
require 'prime'
require 'bigdecimal'
def inp(type=:to_i,spst=" ")
  return eval("gets.chomp.split(#{spst}).map(&:#{type})")
end
def inpf() return self.inp(:to_f," ") end
def inps() return self.inp(:to_s," ") end
def r_up(a, b) (a/b).ceil end
def r_down(a, b) (a/b).floor end
def sum(a) a.inject(:+) end
def big(a,b) return (a>b)? a:b end
def small(a,b) return (a<b)? a:b end
def minp(n,datatype=".to_i")
  t = []
  n.times do
    t.push(eval("gets.chomp#{datatype}"))
  end
  return t
end
def yes() puts "Yes" end
def no() puts "No" end
def ynju(bool,yes="Yes",no="No") puts (bool ? yes : no) end
class Integer
  def divisor_list
    devisors = [1]
    2.upto(self/2) do |i|
      devisors << i if self%i == 0
    end
    devisors << self
    return devisors.uniq.sort
  end
end
class Array
  def upper(a) #aより上
    self.sort.select{|n|n>=a}
  end
  def downer(a) #aより下
    self.sort.select{|n|n<=a}
  end
end
#---------------

s = gets.chomp
n = s.size

if s==s.reverse
  if s[0..((n-1)/2-1)]==s[0..((n-1)/2-1)].reverse
    if s[((n+3)/2-1)..n-1]==s[((n+3)/2-1)..n-1].reverse
      yes
      exit
    end
  end
end
no