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 <bits/stdc++.h>
#define f(i,j,k) for(int i=j;i<k;i++)
#define f2(i,j,k) for(int i=j;i>k;i--)
using namespace std;
int main(){
    long long n,now=0;
    cin>>n;
    string s,t;
    cin>>s>>t;
    while(s[n-1-now]==t[now]){
        now++;
    }
    if(s==t){
        cout<<n<<endl;
    }
    else{
        cout<<2*n-now<<endl;
    }
    return 0;
}