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();
		StringBuilder s = new StringBuilder(sc.next());
		StringBuilder t = new StringBuilder(sc.next());
		sc.close();
		
		int snum = 0;

		int sindex = s.indexOf(t.substring(0, 1));
		
		if (sindex == -1) {
			System.out.println(N*2);
			System.exit(0);
		} else if (sindex == N -1) {
			snum++;
		} else {
			sindex++;
		}

		for (int i = 1; sindex < N; i++, sindex++) {
			if (s.substring(sindex, sindex+1).equals(t.substring(i, i+1))){
			} else {
				break;
			}
			if (sindex == N -1) {
				snum = N - s.indexOf(t.substring(0, 1));
			}
		}


		System.out.println(N * 2 - snum);

	}
}