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 C (GCC 5.4.1) (judge verdict: Accepted)

#include<stdio.h>
#include <stdlib.h>
#include<string.h>
#include<math.h>
#define loop(i, l, r) for(i=l; i<r; i++)/*Instead of function, (for).*/
#define rep(i,r) for(i=0; i<r; i++)
#define Max(a, b) ((a) > (b) ? (a) : (b))
#define Min(a, b) ((a) < (b) ? (a) : (b))
typedef long long int lli;
/*Return Combination ,(nCr)*/
int combi(int n, int r)
{
	if(r==0 || r==n) return 1;
	else return combi(n-1,r) + combi(n-1,r-1);
}
/*Return gcd(a, b)*/
int gcd(int a, int b){
	if(b == 0) return a;
	else return gcd(b, a % b);
}
int main(void)
{
	int i, n, flag = 0;
	scanf("%d", &n);
	if(n%2 != 0) flag = 1;
	char s[n];
	scanf("%s", s);
	rep(i,n/2){
		if(s[i] != s[n/2 + i]) flag = 1;
	}
	if(flag == 1) puts("No");
	else puts("Yes");
	return 0;
}