Problem:
Score : 200 points

Problem Statement

Snuke is interested in strings that satisfy the following conditions:

The length of the string is at least N.

The first N characters equal to the string s.

The last N characters equal to the string t.

Find the length of the shortest string that satisfies the conditions.

Constraints

1≤N≤100

The lengths of s and t are both N.

s and t consist of lowercase English letters.

Input

The input is given from Standard Input in the following format:

N
s
t

Output

Print the length of the shortest string that satisfies the conditions.

Sample Input 1

3
abc
cde

Sample Output 1

5

The shortest string is abcde.

Sample Input 2

1
a
z

Sample Output 2

2

The shortest string is az.

Sample Input 3

4
expr
expr

Sample Output 3

4

The shortest string is expr.

Solution in C (GCC 9.2.1) (judge verdict: Wrong Answer)

#include <stdio.h>
int main(void){
    // Your code here!
    int n=0;
    char s[101]={};
    char t[101]={};
    
    scanf("%d\n",&n);
    gets(s);
    gets(t);
    
    int pos=0;
    for(int i=0;i<n;i++){
        //printf("%c %c ",s[i],t[pos]);
        if(s[i]==t[pos]){
            pos++;
        }else if(pos>0){
            i-=(pos-1);
            pos=0;
        }else{
            pos=0;
        }
        //printf("%d\n",pos);
    }
    printf("%d\n",2*n-pos);
}