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 <bits/stdc++.h>
#define rep(i, n) for (int i=0; i<(int)(n); i++)
#define all(v) v.begin(), v.end()
#define allR(v) v.rbegin(), v.rend()
#define PRINT(v) for (auto x : (v)) cout <<x <<" " ; cout <<endl;
using namespace std;
using ll = long long;
using Graph = vector<vector<int>>;
typedef pair<int,int> Pi;
const ll MOD = 1000000007;
const ll INF = 10000000000000000;
const int inf = 1001001001;
vector<int> x4 = {0, 1, 0, -1}, x8 = {0, 1, 1, 1, 0, -1, -1, -1};
vector<int> y4 = {1, 0, -1, 0}, y8 = {1, 1, 0, -1, -1, -1, 0, 1};
template<class T> inline bool chmin(T& a, T b){if (a>b){a = b; return true;}return false;}
template<class T> inline bool chmax(T& a, T b){if (a<b){a = b; return true;}return false;}
template<class T> inline T powerM(T a,T b){if (b==0) return 1;
T tmp = powerM(a,b/2); if (b%2==0) return tmp*tmp%MOD; else return tmp*tmp%MOD*a%MOD; }
template<class T> inline T power(T a,T b,T m=numeric_limits<T>::max()){ if (b==0) return 1;
  T tmp = power(a,b/2,m); if (b%2==0) return tmp*tmp%m; else return tmp*tmp%m*a%m; }
template<class T> inline T gcd(T a, T b){if (b==0) return a; return gcd(b, a%b);}
template<class T> inline T lcm(T a, T b){return a / gcd(a,b) * b;}
// ax+by=gcd(a,b)を解く
template<class T> inline T extgcd(T a,T b,T &x,T &y){if (b==0){x=1; y=0; return a;} T d=extgcd(b,a%b,y,x); y -= a/b*x; return d;}
void hey(){ cout <<"hey" <<endl; }

template<class T> struct edge { int to; T cost;};


int main() {
  int N; cin >>N;
  string s,t; cin >>s >>t;
  for (int i=0; i<N; i++){
    bool ok = true;
    for (int j=0; j+i<N; j++){
      if (s[i+j] != t[j]) ok = false;
    }
    if (ok){ cout <<N+i <<endl; return 0;}
  }
  cout <<N*2 <<endl;
}