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)

// AGC006_A
#include <iostream>
#include <cstdio>
#include <string>
#include <vector>
#include <iterator>  // std::back_inserter()
#include <tuple>  // std::tuple std::get
#include <set>
#include <map>
#include <unordered_map>
#include <unordered_set>
#include <stack>
#include <queue>
#include <algorithm>  // std::copy()
#include <functional>  // std::greater<T>()
#include <utility>  // std::swap()
#include <numeric>  // accumulate(ALL(vec), 0)  0 は初期値
#include <bitset>  // static_cast<std::bitset<8>>
#include <sstream>  // std::stringstream
#include <cmath>
#include <climits>  // INT_MIN
#include <cctype>  // std::isdigit()
#include <iomanip>  // std::setprecision()
using namespace std;

#define ALL(obj) (obj).begin(), (obj).end()
#define REP(i, n) for (ll i=0; i < n; i++)  // 0 ~ n-1
#define REPN(i, n) for (ll i=1; i <= n; i++)  // 1 ~ n
#define MIN(vec) min_element(ALL((vec)))  // イテレータのため、値を取り出すときは * を先頭につける
#define MAX(vec) max_element(ALL((vec)))
#define IDX(vec, element_iter) distance((vec).begin(), element_iter)
#define SUM(vec) accumulate(ALL((vec)), 0LL)  // 0 は初期値
#define COPY(vec1, vec2) copy(ALL(vec1), back_inserter(vec2))  // vec1をvec2にコピーする vec2は空にしておく必要あり
#define zero_pad(num) setfill('0') << std::right << setw(num)
#define space_pad(num) setfill(' ') << std::right << setw(num)

typedef long long ll;

const ll MOD7 = 1000000007;  // 1 000 000 007
const ll MOD9 = 1000000009;  // 1 000 000 009

int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);

    // input
    ll N;
    string s, t;
    cin >> N >> s >> t;
    
    // calculation
    if (N == 1) {
        if (s == t) {
            cout << 1 << "\n";
        } else {
            cout << 2 << "\n";
        }
    } else {
        ll num_over = N;
        string tmp_s, tmp_t;
        for (ll i = 0; i < N; ++i) {
            tmp_s = s.substr(i, num_over);
            tmp_t = t.substr(0, num_over);
            if (tmp_s == tmp_t) {
                break;
            } else {
                num_over--;
            }
        }
        cout << 2*N - num_over << "\n";
    }
    
    return 0;
}