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: Wrong Answer)

#include <stdio.h>
int equation;
void equal(int,int,char S[]);
int main()
{
    int n;
    scanf("%d",&n);
    char S[105];
    scanf("%s",S);
    equation=0;
    if(n==1||n%2!=0)
        printf("No\n");
    else
    {
        equal(0,n,S);
        if(equation)
        {
            printf("Yes\n");
            printf("Let T= ");
            for(int i=0;i<n/2;i++)
                printf("%c",S[i]);
            printf(", and S=T+T.");
        }
        else
            printf("No\n");
        
    }
}


void equal(int left,int n,char S[])
{
    for(int i=left;i<n/2;i++)
    {
        if(S[i]==S[i+n/2]&&left<=n/2)
        {
            
            left++;
            equal(left,n,S);
        }
        else
            break;
    }
    if(left>=n/2)
        equation=1;
}