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: Wrong Answer)


using namespace std;
using ll=long long;
#include <string>
#include <vector>
#include <cmath>
#include <iostream>
#include <algorithm>
#include <map>
#define out(S) cout<<(S)<<endl;
#define mod(i) ((i)%(ll)(1000000000 + 7))
ll modpow(ll i, ll j) { ll tmp = 1; while (j) { if (j % 2)tmp = mod(tmp*i); i = mod(i*i); j /= 2; }return tmp; }
#define divmod(a,b) (mod(a * modpow((ll)b,(ll)(1e9+5))))
#define For(i,a,b) for(size_t i=(a);i<(b);i++)
#define rFor(i,a,b) for(size_t i=(a)-1;i>=(b);i--)
#define Rep(i,a) for(size_t i=0;i<(a);i++)
#define rRep(i,a) for(size_t i=(a)-1;i>=0;i--)
#define Foreach(item,collection) for(auto item:collection)

vector<int> makeFactor(int x) {
	vector<int> factors;
	factors.push_back(2);
	for (size_t i = 3; i <= sqrt(x); i+=2)
	{
		bool flag = false;
		Foreach(item, factors) if (i%item == 0) { flag = true; break; }
		if (!flag) factors.push_back(i);
	}
	return factors;
}

int main(){
	int N;
	string s, t;
	cin >> N >> s >> t;
	if (s == t) { out(N); return 0; }
	reverse(s.begin(), s.end());
	int ans = N * 2;
	Rep(i, N) {
		if (s[i] == t[i]) {
			ans--;
		}
	}
	out(ans);
	return 0;
}