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 <math.h>
#include <time.h>

int max(int a, int b){
    if(a > b){
        return a;
    }else{
        return b;
    }
}



int main(){
    int N;
    int i;
    char S[N];
    char dammy;
    scanf("%d", &N);
    //printf("%d\n", N);
    scanf("%c", &dammy);
    for(i=0;i<N;i++){
        scanf("%s", &S[i]);
    }

    int ans = 1;
    int hoge = N/2;
    if(N%2==1){
        printf("No\n");
        return 0;
    }else{
        //char T[N/2];
        
        for(i=0;i<hoge;i++){
            if(S[i]==S[i+hoge]){
                ans*=1;
            }else{
                ans*=0;
            }
        }
    if(ans==1){
        printf("Yes\n");
    }else{
        printf("No\n");
    }
   
    return 0;    

    }
    
    

}