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 Java8 (OpenJDK 1.8.0) (judge verdict: Wrong Answer)

import java.util.Scanner;
public class Main {
	public static void main(String[] args){
		Scanner in = new Scanner(System.in);
		int N = in.nextInt();
		String s = in.next();
		String t = in.next();
		int ans;
		if(s.equals(t)) {
			System.out.println(0);
			return;
		}
		String s_sub, t_sub;
		for (int i = 0; i < N; i++) {
			//sのi文字目からN-1文字目まで==tの0文字目からN-i-1文字目までが一致？
			s_sub = s.substring(i, N);
			t_sub = t.substring(0, N-i);
			System.out.println(s_sub+","+t_sub);
			if(s_sub.equals(t_sub)) {
				ans = 2*N - (N-i);
				System.out.println(ans);
				return;
			}
		}
		System.out.println(2*N);
	}
}