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 sc = new Scanner(System.in);
		int N = sc.nextInt();
		String s = sc.next();
		String t = sc.next();
		int ans = N*2;

		if (s.equals(t)) {
			System.out.println(N);
			System.exit(0);
		}

		for (int i = 0; i < N; i++) {
			String sSub = s.substring(N-1-i, N);
			String tSub = t.substring(0, i+1);
			if (sSub.equals(tSub)){
				ans = (N-(i+1))*2 + i+1;
			} else {
				break;
			}
		}

		System.out.println(ans);

		sc.close();
	}
}