Problem:
Score : 200 points

Problem Statement

Given are a positive integer N and a string S of length N consisting of lowercase English letters.

Determine whether the string is a concatenation of two copies of some string.
That is, determine whether there is a string T such that S = T + T.

Constraints

1 \leq N \leq 100

S consists of lowercase English letters.

|S| = N

Input

Input is given from Standard Input in the following format:

N
S

Output

If S is a concatenation of two copies of some string, print Yes; otherwise, print No.

Sample Input 1

6
abcabc

Sample Output 1

Yes

Let T = abc, and S = T + T.

Sample Input 2

6
abcadc

Sample Output 2

No

Sample Input 3

1
z

Sample Output 3

No

Solution in JavaScript (node.js v5.12) (judge verdict: Accepted)

'use strict';
const main = input => {
  const n = parseInt(input[0]);
  const s = input[1];
  let ans = 0;
  for(let i=0; i<n/2; i++) {
    if (s[i] !== s[i+n/2]) {
      ans = 1;
    }
  }
  console.log(ans==1?'No':'Yes');
  
}
main(require("fs").readFileSync("/dev/stdin", "utf8").split('\n'));