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)

/******************************************************************************

                              Online C++ Compiler.
               Code, Compile, Run and Debug C++ program online.
Write your code in this editor and press "Run" button to compile and execute it.

*******************************************************************************/

#include<bits/stdc++.h>
using namespace std;

int in(){
  int a;
  cin >> a;
  return a;
}//int型関数の受け取り

void forin(int* x,int y){
  for (int i=0;i<y;i++){
    cin >> x[i];
  }
}//(x,y) int型配列x[y]の受け取り

int intpow(int x,int y){
  double a=x,b=y;
  return pow(a,b);
}//(x,y) xをy乗

int intfabs(int x){
  double a=x;
  return fabs(a);
}//(x) xの絶対値

int fact(int x){
  if (x == 1) return 1;
  return x*fact(x-1);
}//(x) x!

main(){
    int n=in(),k=in(),a[n],ans=-100000,p=0;
    forin(a,n);
    for (int i=0;i<k;i++) p+=a[i];
    for (int i=0;i+k<=n;i++){
        p+=(a[i+k-1]-a[i]);
        if (ans<p) ans=p;
    }
    cout << ans << endl;
}