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 <iostream>
#include <sstream>
#include <vector>
#include <algorithm>
#include <numeric>
#include <cmath>
#include <utility>
#include <map>
#include <list>
#include <climits>
#include <set>
#include <deque>
#include <stack>
#include <unordered_map>
#include <unordered_set>
#include <iomanip>
#include <bitset>

// #define cerr if(false)cerr
#define watch(x) cerr << "> " << #x << ": " << x << "\n";

using namespace std;

template <typename T>
std::ostream &operator <<(std::ostream &out, vector<T> &v) {
	for (typename vector<T>::size_type i = 0; i < v.size(); ++i)
		out << v[i] << " ";
	out << "\n";
    return out;
}
template <typename T, typename N>
std::ostream &operator <<(std::ostream &out, vector<pair<T, N> > &v) {
	for (size_t i = 0; i < v.size(); ++i)
		out << "(" << v[i].first << ", " << v[i].second << ") ";
	out << "\n";
    return out;
}
template <typename T>
std::ostream &operator <<(std::ostream &out, vector<vector<T> > &v) {
	for (size_t i = 0; i < v.size(); ++i) {
		for (size_t j = 0; j < v[i].size(); ++j) {
			out << v[i][j] << " ";
		}
		out << "\n";
	}
   	return out;
}

bool satisfies(string &s, string &t) {
	if (s.find(t) != string::npos) {
		return true;
	}

	return false;
}

int main() {

	std::ios::sync_with_stdio(false);
	cin.tie(0);
	cout.tie(0);

	int n;
	cin >> n;

	string s, t;
	cin >> s >> t;

	if (satisfies(s, t)) {
		cout << s.size() << "\n";
		return 0;
	}

	for (int i = 0; i < n; ++i) {
		if (s.substr(i, n - i) == t.substr(0, n - i)) {
			cout << n + i << "\n";
			return 0;
		}
	}

	cout << 2 * n << "\n";

	return 0;

}