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: Accepted)

#include <bits/stdc++.h>
using namespace std;

#define all(v) v.begin(), v.end()
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define intll int long long
const int INF = 1e9;
const int MOD = 1e9 + 7;

int main() {
  int n ; 
  cin >> n ;
  string s , t  ;
  cin >> s >> t ;
  deque<char> S , T ;
  rep(i,n){
    S.push_back(s.at(i)) ;
    T.push_back(t.at(i));
  }
  if(s == t ) {
    cout << s.size() <<endl ; 
    return 0 ;
  }
  
  int ans = 2 * n ;
  
  rep(i,n){
    S.pop_front();
    T.pop_back();
    
    if( S == T){
      ans = S.size() + 2*(i+1) ;
      cout <<  ans <<endl ;
      return 0 ;
    }
  }
    
  
}