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 JavaScript (node.js v5.12) (judge verdict: Wrong Answer)

function main(input) {
  const S = input;

  for (var i = 0; i < Math.floor(S.length / 2); i++) {
    if (S[i] !== S[S.length - (i + 1)]) {
      console.log("No");
      return;
    }
  }
  const firstS = S.slice(0, (S.length - 1) / 2);
  const lastS = S.slice((S.length + 3) / 2 - 1);

  for (var i = 0; i < Math.floor(firstS.length / 2); i++) {
    if (firstS[i] !== firstS[firstS.length - (i + 1)]) {
      console.log("No");
      return;
    }
  }

  for (var i = 0; i < Math.floor(lastS.length / 2); i++) {
    if (lastS[i] !== lastS[lastS.length - (i + 1)]) {
      console.log("No");
      return;
    }
  }

  console.log("Yes");
}

main(require("fs").readFileSync("/dev/stdin", "utf8"));