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)

#include <bits/stdc++.h>
#include <regex>

using namespace std;
template<typename T> void in(T &x) { x = 0; bool neg = false; register T c = getchar(); if (c == '-')neg = true, c = getchar(); while ((c < 48) || (c > 57))c = getchar(); for (; c < 48 || c > 57; c = getchar()); for (; c > 47 && c < 58; c = getchar())x = (x << 3) + (x << 1) + (c & 15); if (neg) x *= -1; }
template<typename T> void out(T n) { bool neg = 0; if (n < 0)n *= -1, neg = 1; char snum[65]; int i = 0; do { snum[i++] = n % 10 + '0'; n /= 10; } while (n); --i; if (neg)putchar('-'); while (i >= 0)putchar(snum[i--]); }
template<typename T> void outln(T n) { bool neg = 0; if (n < 0)n *= -1, neg = 1; char snum[65]; int i = 0; do { snum[i++] = n % 10 + '0'; n /= 10; } while (n); --i; if (neg)putchar('-'); while (i >= 0)putchar(snum[i--]); putchar('\n'); }
#define len(_x) (sizeof((_x)) / sizeof(_x)[0])
//#define fastIO 
#define ll long long
#define itr(_c) for(auto i=_c.begin();i!=_c.end();i++)
#define itrr(_c)for(auto i=_c.begin();i!=_c.end();i++)
#define f1(_x)for (int i = 0; i < _x; ++i)
#define fr(_x)for (int i = _x; i >0; i--)
#define f2(_x,_y)for (int i = _x; i < _y; ++i)
#define fileIO 	freopen("input.txt", "r", stdin);freopen("output.txt", "w", stdout);
typedef vector<int> vi; typedef vector<string> vs; typedef vector<bool> vb; vector<long long>vll;
typedef pair<int, int> ii;
typedef vector<ii> vii;
typedef set<int> si;
typedef map<string, int> msi;
void fastIO(){ ios_base::sync_with_stdio(false); cin.tie(false); }
int main() {
	fastIO();
	int n,cnt=0; string s, t;
	cin >> n >> s >> t;
	int i = 1;
	for (; i < n+1; ++i)
	{
		if(s.substr(s.size() - i )==t.substr(0,i))break;
		if (i == n ) { std::cout << 2 * n; return 0; }
	}
	std::cout << 2*n-i;
		
	
	

	
}