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++14 (GCC 5.4.1) (judge verdict: Accepted)

#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define rng(i, a, b) for (int i = int(a); i < int(b); i++)
#define rep(i, b) rng(i, 0, b)
#define gnr(i, a, b) for (int i = int(b) - 1; i >= int(a); i--)
#define per(i, b) gnr(i, 0, b)
#define bg begin()
#define ed end()
#define all(x) x.bg, x.ed
#define vi vector<int>
template <class t, class u>
bool chmax(t &a, u b)
{
    if (a < b)
    {
        a = b;
        return true;
    }
    return false;
}
template <class t, class u>
bool chmin(t &a, u b)
{
    if (b < a)
    {
        a = b;
        return true;
    }
    return false;
}

int main()
{
    string s, t;
    int n;
    cin >> n;
    cin >> s >> t;
    for (int i = n; i >= 0; i--)
    {
        //        cout << "a:" << s.substr(n - i, i) << " " << t.substr(0, i) << endl;
        if (s.substr(n - i, i) == t.substr(0, i))
        {
            string aaaaa= s +t.substr(i);
            cout << aaaaa.length() << endl;
            break;
        }
    }
    return 0;
}