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)

function main(input) {
    const args = input.split('\n');
    const N = parseInt(args[0], 10),
          S = args[1];
    var str = S.substr(0, N / 2);
    if (str + str == S) {
      console.log("Yes");
    } else {
      console.log("No");
    }
}
main(require('fs').readFileSync('/dev/stdin', 'utf8'));