agc006a.cpp

#include <vector>
#include <list>
#include <map>
#include <set>
#include <queue>
#include <deque>
#include <stack>
#include <algorithm>
#include <functional>
#include <numeric>
#include <utility>
#include <sstream>
#include <iostream>
#include <iomanip>
#include <cstdio>
#include <cmath>
#include <cstdlib>
#include <cctype>
#include <string>
#include <cstring>
using namespace std;
#define REP(i,n) for(int i = 0; i < (int)(n); i++)
#define FOR(i,a,b) for(int i = (a); i < (int)(b); i++)
#define pb push_back
#define mp make_pair
typedef vector<int> vi;
typedef pair<int, int> pi;
typedef long long ll;
typedef unsigned long long ull;
const int IINF = 1<<28;
const ll MOD = 1000000007;
const int dx[] = {1, 0, -1, 0}, dy[] = {0, 1, 0, -1};

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

	int n;
	string s, t;
	cin >> n >> s >> t;
	int cnt;
	REP(i, s.size()) {
		cnt = 0;
		REP(j, t.size())
			if(s[i+j] == t[j]) cnt++;
		if(cnt == s.size() || cnt == t.size()) break;
	}
	int ans = s.size() + t.size() - cnt;
	if(ans < n) ans = n;
	cout << ans << endl;

	return 0;
}