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 Common Lisp (SBCL 2.0.3) (judge verdict: Accepted)

(defun app ()
    (let* ((s (read-line))
        (n (length s))
        (ans "Yes"))
        (dotimes (i (floor (/ n 2)))
            (if (not (equal (subseq s i (+ i 1)) (subseq s (- n i 1) (- n i))))
                (setq ans "No")
            )
        )
        (if (equal ans "Yes")
            (dotimes (i (floor (/ (- n 1) 2)))
                (if (not (equal (subseq s i (+ i 1)) (subseq s (- (floor (/ (- n 1) 2)) i 1) (- (floor (/ (- n 1) 2)) i))))
                (setq ans "No")
                )
            )
        )
        (if (equal ans "Yes")
            (let ((num (floor (/ (+ n 3) 2))))
            (loop for i from 0 to (floor (/ (- n num) 2)) do
                (if (not (equal (subseq s (- (+ num i) 1) (+ num i)) (subseq s (- n i 1) (- n i))))
                (setq ans "No")
                )
            )
            )
        )

        (format t "~A~%" ans)
    )
)
(app)